<?xml version="1.0" encoding="US-ASCII"?>
<!-- Generated by Fujitsu XWand B0150 -->
<link:linkbase xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xmlns:xlink="http://www.w3.org/1999/xlink">
  <link:roleRef roleURI="http://www.wfscorp.com/role/CashFlows" xlink:type="simple" xlink:href="int-20110630.xsd#CashFlows"/>
  <link:roleRef roleURI="http://www.wfscorp.com/role/BalanceSheet" xlink:type="simple" xlink:href="int-20110630.xsd#BalanceSheet"/>
  <link:roleRef roleURI="http://www.wfscorp.com/role/StatementOfIncome" xlink:type="simple" xlink:href="int-20110630.xsd#StatementOfIncome"/>
  <link:roleRef roleURI="http://www.wfscorp.com/role/StatementsOfShareholdersEquityAndComprehensiveIncome" xlink:type="simple" xlink:href="int-20110630.xsd#StatementsOfShareholdersEquityAndComprehensiveIncome"/>
  <link:roleRef roleURI="http://www.wfscorp.com/role/StatementsOfShareholdersEquityAndComprehensiveIncomeCalc2" xlink:type="simple" xlink:href="int-20110630.xsd#StatementsOfShareholdersEquityAndComprehensiveIncomeCalc2"/>
  <link:roleRef roleURI="http://www.wfscorp.com/role/DisclosureEarningsPerCommonShareDetails" xlink:type="simple" xlink:href="int-20110630.xsd#DisclosureEarningsPerCommonShareDetails"/>
  <link:roleRef roleURI="http://www.wfscorp.com/role/DisclosureDebtDetails" xlink:type="simple" xlink:href="int-20110630.xsd#DisclosureDebtDetails"/>
  <link:calculationLink xlink:type="extended" xlink:role="http://www.wfscorp.com/role/StatementsOfShareholdersEquityAndComprehensiveIncomeCalc2">
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest" xlink:label="ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest" xlink:title="ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_ProfitLoss" xlink:label="ProfitLoss" xlink:title="ProfitLoss"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest" xlink:to="ProfitLoss" xlink:title="calculation: ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest to ProfitLoss" use="optional" order="1.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossArisingDuringPeriodNetOfTax" xlink:label="OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossArisingDuringPeriodNetOfTax" xlink:title="OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossArisingDuringPeriodNetOfTax"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest" xlink:to="OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossArisingDuringPeriodNetOfTax" xlink:title="calculation: ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest to OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossArisingDuringPeriodNetOfTax" use="optional" order="2.0" weight="1.0"/>
  </link:calculationLink>
  <link:calculationLink xlink:type="extended" xlink:role="http://www.wfscorp.com/role/DisclosureEarningsPerCommonShareDetails">
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" xlink:label="WeightedAverageNumberOfDilutedSharesOutstanding" xlink:title="WeightedAverageNumberOfDilutedSharesOutstanding"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" xlink:label="WeightedAverageNumberOfSharesOutstandingBasic" xlink:title="WeightedAverageNumberOfSharesOutstandingBasic"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="WeightedAverageNumberOfDilutedSharesOutstanding" xlink:to="WeightedAverageNumberOfSharesOutstandingBasic" xlink:title="calculation: WeightedAverageNumberOfDilutedSharesOutstanding to WeightedAverageNumberOfSharesOutstandingBasic" order="1.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment" xlink:label="WeightedAverageNumberDilutedSharesOutstandingAdjustment" xlink:title="WeightedAverageNumberDilutedSharesOutstandingAdjustment"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="WeightedAverageNumberOfDilutedSharesOutstanding" xlink:to="WeightedAverageNumberDilutedSharesOutstandingAdjustment" xlink:title="calculation: WeightedAverageNumberOfDilutedSharesOutstanding to WeightedAverageNumberDilutedSharesOutstandingAdjustment" order="2.0" weight="1.0"/>
  </link:calculationLink>
  <link:calculationLink xlink:type="extended" xlink:role="http://www.wfscorp.com/role/CashFlows">
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease" xlink:label="CashAndCashEquivalentsPeriodIncreaseDecrease" xlink:title="CashAndCashEquivalentsPeriodIncreaseDecrease"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:label="NetCashProvidedByUsedInOperatingActivities" xlink:title="NetCashProvidedByUsedInOperatingActivities"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="CashAndCashEquivalentsPeriodIncreaseDecrease" xlink:to="NetCashProvidedByUsedInOperatingActivities" xlink:title="calculation: CashAndCashEquivalentsPeriodIncreaseDecrease to NetCashProvidedByUsedInOperatingActivities" order="1.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_ProfitLoss" xlink:label="ProfitLoss" xlink:title="ProfitLoss"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="NetCashProvidedByUsedInOperatingActivities" xlink:to="ProfitLoss" xlink:title="calculation: NetCashProvidedByUsedInOperatingActivities to ProfitLoss" order="1.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities" xlink:label="AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities" xlink:title="AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="NetCashProvidedByUsedInOperatingActivities" xlink:to="AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities" xlink:title="calculation: NetCashProvidedByUsedInOperatingActivities to AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities" order="2.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DepreciationAndAmortization" xlink:label="DepreciationAndAmortization" xlink:title="DepreciationAndAmortization"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities" xlink:to="DepreciationAndAmortization" xlink:title="calculation: AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities to DepreciationAndAmortization" order="1.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_ProvisionForDoubtfulAccounts" xlink:label="ProvisionForDoubtfulAccounts" xlink:title="ProvisionForDoubtfulAccounts"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities" xlink:to="ProvisionForDoubtfulAccounts" xlink:title="calculation: AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities to ProvisionForDoubtfulAccounts" order="2.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_GainLossOnInvestments" xlink:label="GainLossOnInvestments" xlink:title="GainLossOnInvestments"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities" xlink:to="GainLossOnInvestments" xlink:title="calculation: AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities to GainLossOnInvestments" order="3.0" weight="-1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DeferredIncomeTaxExpenseBenefit" xlink:label="DeferredIncomeTaxExpenseBenefit" xlink:title="DeferredIncomeTaxExpenseBenefit"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities" xlink:to="DeferredIncomeTaxExpenseBenefit" xlink:title="calculation: AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities to DeferredIncomeTaxExpenseBenefit" order="4.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_ShareBasedCompensation" xlink:label="ShareBasedCompensation" xlink:title="ShareBasedCompensation"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities" xlink:to="ShareBasedCompensation" xlink:title="calculation: AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities to ShareBasedCompensation" order="5.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_ForeignCurrencyTransactionGainLossUnrealized" xlink:label="ForeignCurrencyTransactionGainLossUnrealized" xlink:title="ForeignCurrencyTransactionGainLossUnrealized"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities" xlink:to="ForeignCurrencyTransactionGainLossUnrealized" xlink:title="calculation: AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities to ForeignCurrencyTransactionGainLossUnrealized" order="6.0" weight="-1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_IncreaseDecreaseInAccountsReceivable" xlink:label="IncreaseDecreaseInAccountsReceivable" xlink:title="IncreaseDecreaseInAccountsReceivable"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities" xlink:to="IncreaseDecreaseInAccountsReceivable" xlink:title="calculation: AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities to IncreaseDecreaseInAccountsReceivable" order="8.0" weight="-1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_IncreaseDecreaseInInventories" xlink:label="IncreaseDecreaseInInventories" xlink:title="IncreaseDecreaseInInventories"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities" xlink:to="IncreaseDecreaseInInventories" xlink:title="calculation: AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities to IncreaseDecreaseInInventories" order="9.0" weight="-1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_IncreaseDecreaseInPrepaidExpense" xlink:label="IncreaseDecreaseInPrepaidExpense" xlink:title="IncreaseDecreaseInPrepaidExpense"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities" xlink:to="IncreaseDecreaseInPrepaidExpense" xlink:title="calculation: AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities to IncreaseDecreaseInPrepaidExpense" order="10.0" weight="-1.0"/>
    <link:loc xlink:type="locator" xlink:href="int-20110630.xsd#int_IncreaseDecreaseInTransactionTaxesReceivable" xlink:label="IncreaseDecreaseInTransactionTaxesReceivable" xlink:title="IncreaseDecreaseInTransactionTaxesReceivable"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities" xlink:to="IncreaseDecreaseInTransactionTaxesReceivable" xlink:title="calculation: AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities to IncreaseDecreaseInTransactionTaxesReceivable" order="11.0" weight="-1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_IncreaseDecreaseInOtherOperatingAssets" xlink:label="IncreaseDecreaseInOtherOperatingAssets" xlink:title="IncreaseDecreaseInOtherOperatingAssets"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities" xlink:to="IncreaseDecreaseInOtherOperatingAssets" xlink:title="calculation: AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities to IncreaseDecreaseInOtherOperatingAssets" order="12.0" weight="-1.0"/>
    <link:loc xlink:type="locator" xlink:href="int-20110630.xsd#int_IncreaseDecreaseInShortTermDerivativeAssets" xlink:label="IncreaseDecreaseInShortTermDerivativeAssets" xlink:title="IncreaseDecreaseInShortTermDerivativeAssets"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities" xlink:to="IncreaseDecreaseInShortTermDerivativeAssets" xlink:title="calculation: AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities to IncreaseDecreaseInShortTermDerivativeAssets" order="13.0" weight="-1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_IncreaseDecreaseInOtherNoncurrentAssets" xlink:label="IncreaseDecreaseInOtherNoncurrentAssets" xlink:title="IncreaseDecreaseInOtherNoncurrentAssets"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities" xlink:to="IncreaseDecreaseInOtherNoncurrentAssets" xlink:title="calculation: AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities to IncreaseDecreaseInOtherNoncurrentAssets" order="14.0" weight="-1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_IncreaseDecreaseInAccountsPayable" xlink:label="IncreaseDecreaseInAccountsPayable" xlink:title="IncreaseDecreaseInAccountsPayable"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities" xlink:to="IncreaseDecreaseInAccountsPayable" xlink:title="calculation: AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities to IncreaseDecreaseInAccountsPayable" order="15.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_IncreaseDecreaseInCustomerDeposits" xlink:label="IncreaseDecreaseInCustomerDeposits" xlink:title="IncreaseDecreaseInCustomerDeposits"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities" xlink:to="IncreaseDecreaseInCustomerDeposits" xlink:title="calculation: AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities to IncreaseDecreaseInCustomerDeposits" order="16.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="int-20110630.xsd#int_IncreaseDecreaseInTransactionTaxesPayable" xlink:label="IncreaseDecreaseInTransactionTaxesPayable" xlink:title="IncreaseDecreaseInTransactionTaxesPayable"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities" xlink:to="IncreaseDecreaseInTransactionTaxesPayable" xlink:title="calculation: AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities to IncreaseDecreaseInTransactionTaxesPayable" order="17.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="int-20110630.xsd#int_IncreaseDecreaseInShortTermDerivativeLiabilities" xlink:label="IncreaseDecreaseInShortTermDerivativeLiabilities" xlink:title="IncreaseDecreaseInShortTermDerivativeLiabilities"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities" xlink:to="IncreaseDecreaseInShortTermDerivativeLiabilities" xlink:title="calculation: AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities to IncreaseDecreaseInShortTermDerivativeLiabilities" order="18.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="int-20110630.xsd#int_IncreaseDecreaseInAccruedExpensesAndOtherLiabilities" xlink:label="IncreaseDecreaseInAccruedExpensesAndOtherLiabilities" xlink:title="IncreaseDecreaseInAccruedExpensesAndOtherLiabilities"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities" xlink:to="IncreaseDecreaseInAccruedExpensesAndOtherLiabilities" xlink:title="calculation: AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities to IncreaseDecreaseInAccruedExpensesAndOtherLiabilities" order="19.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="int-20110630.xsd#int_IncreaseDecreaseInIncomeTaxAndOtherLiabilitiesNoncurrent" xlink:label="IncreaseDecreaseInIncomeTaxAndOtherLiabilitiesNoncurrent" xlink:title="IncreaseDecreaseInIncomeTaxAndOtherLiabilitiesNoncurrent"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities" xlink:to="IncreaseDecreaseInIncomeTaxAndOtherLiabilitiesNoncurrent" xlink:title="calculation: AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities to IncreaseDecreaseInIncomeTaxAndOtherLiabilitiesNoncurrent" order="20.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_OtherNoncashIncomeExpense" xlink:label="OtherNoncashIncomeExpense" xlink:title="OtherNoncashIncomeExpense"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities" xlink:to="OtherNoncashIncomeExpense" xlink:title="calculation: AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities to OtherNoncashIncomeExpense" order="7.0" weight="-1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivities" xlink:label="NetCashProvidedByUsedInInvestingActivities" xlink:title="NetCashProvidedByUsedInInvestingActivities"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="CashAndCashEquivalentsPeriodIncreaseDecrease" xlink:to="NetCashProvidedByUsedInInvestingActivities" xlink:title="calculation: CashAndCashEquivalentsPeriodIncreaseDecrease to NetCashProvidedByUsedInInvestingActivities" order="2.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_PaymentsToAcquirePropertyPlantAndEquipment" xlink:label="PaymentsToAcquirePropertyPlantAndEquipment" xlink:title="PaymentsToAcquirePropertyPlantAndEquipment"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="NetCashProvidedByUsedInInvestingActivities" xlink:to="PaymentsToAcquirePropertyPlantAndEquipment" xlink:title="calculation: NetCashProvidedByUsedInInvestingActivities to PaymentsToAcquirePropertyPlantAndEquipment" order="1.0" weight="-1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired" xlink:label="PaymentsToAcquireBusinessesNetOfCashAcquired" xlink:title="PaymentsToAcquireBusinessesNetOfCashAcquired"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="NetCashProvidedByUsedInInvestingActivities" xlink:to="PaymentsToAcquireBusinessesNetOfCashAcquired" xlink:title="calculation: NetCashProvidedByUsedInInvestingActivities to PaymentsToAcquireBusinessesNetOfCashAcquired" order="4.0" weight="-1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_PaymentsToAcquireNotesReceivable" xlink:label="PaymentsToAcquireNotesReceivable" xlink:title="PaymentsToAcquireNotesReceivable"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="NetCashProvidedByUsedInInvestingActivities" xlink:to="PaymentsToAcquireNotesReceivable" xlink:title="calculation: NetCashProvidedByUsedInInvestingActivities to PaymentsToAcquireNotesReceivable" use="optional" order="2.0" weight="-1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_ProceedsFromCollectionOfNotesReceivable" xlink:label="ProceedsFromCollectionOfNotesReceivable" xlink:title="ProceedsFromCollectionOfNotesReceivable"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="NetCashProvidedByUsedInInvestingActivities" xlink:to="ProceedsFromCollectionOfNotesReceivable" xlink:title="calculation: NetCashProvidedByUsedInInvestingActivities to ProceedsFromCollectionOfNotesReceivable" use="optional" order="3.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:label="NetCashProvidedByUsedInFinancingActivities" xlink:title="NetCashProvidedByUsedInFinancingActivities"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="CashAndCashEquivalentsPeriodIncreaseDecrease" xlink:to="NetCashProvidedByUsedInFinancingActivities" xlink:title="calculation: CashAndCashEquivalentsPeriodIncreaseDecrease to NetCashProvidedByUsedInFinancingActivities" order="3.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_PaymentsOfDividendsCommonStock" xlink:label="PaymentsOfDividendsCommonStock" xlink:title="PaymentsOfDividendsCommonStock"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="NetCashProvidedByUsedInFinancingActivities" xlink:to="PaymentsOfDividendsCommonStock" xlink:title="calculation: NetCashProvidedByUsedInFinancingActivities to PaymentsOfDividendsCommonStock" order="1.0" weight="-1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_ProceedsFromLinesOfCredit" xlink:label="ProceedsFromLinesOfCredit" xlink:title="ProceedsFromLinesOfCredit"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="NetCashProvidedByUsedInFinancingActivities" xlink:to="ProceedsFromLinesOfCredit" xlink:title="calculation: NetCashProvidedByUsedInFinancingActivities to ProceedsFromLinesOfCredit" order="3.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_RepaymentsOfLinesOfCredit" xlink:label="RepaymentsOfLinesOfCredit" xlink:title="RepaymentsOfLinesOfCredit"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="NetCashProvidedByUsedInFinancingActivities" xlink:to="RepaymentsOfLinesOfCredit" xlink:title="calculation: NetCashProvidedByUsedInFinancingActivities to RepaymentsOfLinesOfCredit" order="4.0" weight="-1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_RepaymentsOfOtherDebt" xlink:label="RepaymentsOfOtherDebt" xlink:title="RepaymentsOfOtherDebt"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="NetCashProvidedByUsedInFinancingActivities" xlink:to="RepaymentsOfOtherDebt" xlink:title="calculation: NetCashProvidedByUsedInFinancingActivities to RepaymentsOfOtherDebt" order="5.0" weight="-1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_ProceedsFromStockOptionsExercised" xlink:label="ProceedsFromStockOptionsExercised" xlink:title="ProceedsFromStockOptionsExercised"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="NetCashProvidedByUsedInFinancingActivities" xlink:to="ProceedsFromStockOptionsExercised" xlink:title="calculation: NetCashProvidedByUsedInFinancingActivities to ProceedsFromStockOptionsExercised" order="6.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_ExcessTaxBenefitFromShareBasedCompensationFinancingActivities" xlink:label="ExcessTaxBenefitFromShareBasedCompensationFinancingActivities" xlink:title="ExcessTaxBenefitFromShareBasedCompensationFinancingActivities"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="NetCashProvidedByUsedInFinancingActivities" xlink:to="ExcessTaxBenefitFromShareBasedCompensationFinancingActivities" xlink:title="calculation: NetCashProvidedByUsedInFinancingActivities to ExcessTaxBenefitFromShareBasedCompensationFinancingActivities" order="7.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="int-20110630.xsd#int_PaymentsForRepurchaseOfCommonStockToSatisfyEmployeeTaxWithholdingObligations" xlink:label="PaymentsForRepurchaseOfCommonStockToSatisfyEmployeeTaxWithholdingObligations" xlink:title="PaymentsForRepurchaseOfCommonStockToSatisfyEmployeeTaxWithholdingObligations"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="NetCashProvidedByUsedInFinancingActivities" xlink:to="PaymentsForRepurchaseOfCommonStockToSatisfyEmployeeTaxWithholdingObligations" xlink:title="calculation: NetCashProvidedByUsedInFinancingActivities to PaymentsForRepurchaseOfCommonStockToSatisfyEmployeeTaxWithholdingObligations" order="8.0" weight="-1.0"/>
    <link:loc xlink:type="locator" xlink:href="int-20110630.xsd#int_PaymentOfAssumedEmployeeBenefits" xlink:label="PaymentOfAssumedEmployeeBenefits" xlink:title="PaymentOfAssumedEmployeeBenefits"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="NetCashProvidedByUsedInFinancingActivities" xlink:to="PaymentOfAssumedEmployeeBenefits" xlink:title="calculation: NetCashProvidedByUsedInFinancingActivities to PaymentOfAssumedEmployeeBenefits" use="optional" order="2.0" weight="-1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_ProceedsFromMinorityShareholders" xlink:label="ProceedsFromMinorityShareholders" xlink:title="ProceedsFromMinorityShareholders"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="NetCashProvidedByUsedInFinancingActivities" xlink:to="ProceedsFromMinorityShareholders" xlink:title="calculation: NetCashProvidedByUsedInFinancingActivities to ProceedsFromMinorityShareholders" order="4.5" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_EffectOfExchangeRateOnCashAndCashEquivalents" xlink:label="EffectOfExchangeRateOnCashAndCashEquivalents" xlink:title="EffectOfExchangeRateOnCashAndCashEquivalents"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="CashAndCashEquivalentsPeriodIncreaseDecrease" xlink:to="EffectOfExchangeRateOnCashAndCashEquivalents" xlink:title="calculation: CashAndCashEquivalentsPeriodIncreaseDecrease to EffectOfExchangeRateOnCashAndCashEquivalents" order="4.0" weight="1.0"/>
  </link:calculationLink>
  <link:calculationLink xlink:type="extended" xlink:role="http://www.wfscorp.com/role/BalanceSheet">
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_Assets" xlink:label="Assets" xlink:title="Assets"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_AssetsCurrent" xlink:label="AssetsCurrent" xlink:title="AssetsCurrent"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="Assets" xlink:to="AssetsCurrent" xlink:title="calculation: Assets to AssetsCurrent" order="1.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:label="CashAndCashEquivalentsAtCarryingValue" xlink:title="CashAndCashEquivalentsAtCarryingValue"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="AssetsCurrent" xlink:to="CashAndCashEquivalentsAtCarryingValue" xlink:title="calculation: AssetsCurrent to CashAndCashEquivalentsAtCarryingValue" order="1.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_AccountsReceivableNetCurrent" xlink:label="AccountsReceivableNetCurrent" xlink:title="AccountsReceivableNetCurrent"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="AssetsCurrent" xlink:to="AccountsReceivableNetCurrent" xlink:title="calculation: AssetsCurrent to AccountsReceivableNetCurrent" order="2.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_InventoryNet" xlink:label="InventoryNet" xlink:title="InventoryNet"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="AssetsCurrent" xlink:to="InventoryNet" xlink:title="calculation: AssetsCurrent to InventoryNet" order="3.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_PrepaidExpenseCurrent" xlink:label="PrepaidExpenseCurrent" xlink:title="PrepaidExpenseCurrent"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="AssetsCurrent" xlink:to="PrepaidExpenseCurrent" xlink:title="calculation: AssetsCurrent to PrepaidExpenseCurrent" order="4.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="int-20110630.xsd#int_TransactionTaxesReceivable" xlink:label="TransactionTaxesReceivable" xlink:title="TransactionTaxesReceivable"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="AssetsCurrent" xlink:to="TransactionTaxesReceivable" xlink:title="calculation: AssetsCurrent to TransactionTaxesReceivable" order="5.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DerivativeAssetsCurrent" xlink:label="DerivativeAssetsCurrent" xlink:title="DerivativeAssetsCurrent"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="AssetsCurrent" xlink:to="DerivativeAssetsCurrent" xlink:title="calculation: AssetsCurrent to DerivativeAssetsCurrent" order="6.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_OtherAssetsCurrent" xlink:label="OtherAssetsCurrent" xlink:title="OtherAssetsCurrent"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="AssetsCurrent" xlink:to="OtherAssetsCurrent" xlink:title="calculation: AssetsCurrent to OtherAssetsCurrent" order="7.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet" xlink:label="PropertyPlantAndEquipmentNet" xlink:title="PropertyPlantAndEquipmentNet"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="Assets" xlink:to="PropertyPlantAndEquipmentNet" xlink:title="calculation: Assets to PropertyPlantAndEquipmentNet" order="2.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_Goodwill" xlink:label="Goodwill" xlink:title="Goodwill"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="Assets" xlink:to="Goodwill" xlink:title="calculation: Assets to Goodwill" order="3.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_IntangibleAssetsNetExcludingGoodwill" xlink:label="IntangibleAssetsNetExcludingGoodwill" xlink:title="IntangibleAssetsNetExcludingGoodwill"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="Assets" xlink:to="IntangibleAssetsNetExcludingGoodwill" xlink:title="calculation: Assets to IntangibleAssetsNetExcludingGoodwill" order="4.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_OtherAssetsNoncurrent" xlink:label="OtherAssetsNoncurrent" xlink:title="OtherAssetsNoncurrent"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="Assets" xlink:to="OtherAssetsNoncurrent" xlink:title="calculation: Assets to OtherAssetsNoncurrent" order="5.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_LiabilitiesAndStockholdersEquity" xlink:label="LiabilitiesAndStockholdersEquity" xlink:title="LiabilitiesAndStockholdersEquity"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_Liabilities" xlink:label="Liabilities" xlink:title="Liabilities"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="LiabilitiesAndStockholdersEquity" xlink:to="Liabilities" xlink:title="calculation: LiabilitiesAndStockholdersEquity to Liabilities" order="1.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_LiabilitiesCurrent" xlink:label="LiabilitiesCurrent" xlink:title="LiabilitiesCurrent"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="Liabilities" xlink:to="LiabilitiesCurrent" xlink:title="calculation: Liabilities to LiabilitiesCurrent" order="1.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DebtCurrent" xlink:label="DebtCurrent" xlink:title="DebtCurrent"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="LiabilitiesCurrent" xlink:to="DebtCurrent" xlink:title="calculation: LiabilitiesCurrent to DebtCurrent" order="1.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_AccountsPayableCurrent" xlink:label="AccountsPayableCurrent" xlink:title="AccountsPayableCurrent"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="LiabilitiesCurrent" xlink:to="AccountsPayableCurrent" xlink:title="calculation: LiabilitiesCurrent to AccountsPayableCurrent" order="2.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_CustomerDepositsCurrent" xlink:label="CustomerDepositsCurrent" xlink:title="CustomerDepositsCurrent"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="LiabilitiesCurrent" xlink:to="CustomerDepositsCurrent" xlink:title="calculation: LiabilitiesCurrent to CustomerDepositsCurrent" order="3.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="int-20110630.xsd#int_TransactionTaxesPayable" xlink:label="TransactionTaxesPayable" xlink:title="TransactionTaxesPayable"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="LiabilitiesCurrent" xlink:to="TransactionTaxesPayable" xlink:title="calculation: LiabilitiesCurrent to TransactionTaxesPayable" order="4.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DerivativeLiabilitiesCurrent" xlink:label="DerivativeLiabilitiesCurrent" xlink:title="DerivativeLiabilitiesCurrent"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="LiabilitiesCurrent" xlink:to="DerivativeLiabilitiesCurrent" xlink:title="calculation: LiabilitiesCurrent to DerivativeLiabilitiesCurrent" order="5.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="int-20110630.xsd#int_AccruedExpensesAndOtherCurrentLiabilities" xlink:label="AccruedExpensesAndOtherCurrentLiabilities" xlink:title="AccruedExpensesAndOtherCurrentLiabilities"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="LiabilitiesCurrent" xlink:to="AccruedExpensesAndOtherCurrentLiabilities" xlink:title="calculation: LiabilitiesCurrent to AccruedExpensesAndOtherCurrentLiabilities" order="6.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_LongTermDebtNoncurrent" xlink:label="LongTermDebtNoncurrent" xlink:title="LongTermDebtNoncurrent"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="Liabilities" xlink:to="LongTermDebtNoncurrent" xlink:title="calculation: Liabilities to LongTermDebtNoncurrent" order="2.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_AccruedIncomeTaxesNoncurrent" xlink:label="AccruedIncomeTaxesNoncurrent" xlink:title="AccruedIncomeTaxesNoncurrent"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="Liabilities" xlink:to="AccruedIncomeTaxesNoncurrent" xlink:title="calculation: Liabilities to AccruedIncomeTaxesNoncurrent" order="3.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="int-20110630.xsd#int_DeferredCompensationLiabilityClassifiedAndOtherLiabilitiesNoncurrent" xlink:label="DeferredCompensationLiabilityClassifiedAndOtherLiabilitiesNoncurrent" xlink:title="DeferredCompensationLiabilityClassifiedAndOtherLiabilitiesNoncurrent"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="Liabilities" xlink:to="DeferredCompensationLiabilityClassifiedAndOtherLiabilitiesNoncurrent" xlink:title="calculation: Liabilities to DeferredCompensationLiabilityClassifiedAndOtherLiabilitiesNoncurrent" order="4.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" xlink:label="StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" xlink:title="StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="LiabilitiesAndStockholdersEquity" xlink:to="StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" xlink:title="calculation: LiabilitiesAndStockholdersEquity to StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" order="2.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_StockholdersEquity" xlink:label="StockholdersEquity" xlink:title="StockholdersEquity"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" xlink:to="StockholdersEquity" xlink:title="calculation: StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest to StockholdersEquity" order="1.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_PreferredStockValue" xlink:label="PreferredStockValue" xlink:title="PreferredStockValue"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="StockholdersEquity" xlink:to="PreferredStockValue" xlink:title="calculation: StockholdersEquity to PreferredStockValue" order="1.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_CommonStockValue" xlink:label="CommonStockValue" xlink:title="CommonStockValue"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="StockholdersEquity" xlink:to="CommonStockValue" xlink:title="calculation: StockholdersEquity to CommonStockValue" order="2.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_AdditionalPaidInCapital" xlink:label="AdditionalPaidInCapital" xlink:title="AdditionalPaidInCapital"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="StockholdersEquity" xlink:to="AdditionalPaidInCapital" xlink:title="calculation: StockholdersEquity to AdditionalPaidInCapital" order="3.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_RetainedEarningsAccumulatedDeficit" xlink:label="RetainedEarningsAccumulatedDeficit" xlink:title="RetainedEarningsAccumulatedDeficit"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="StockholdersEquity" xlink:to="RetainedEarningsAccumulatedDeficit" xlink:title="calculation: StockholdersEquity to RetainedEarningsAccumulatedDeficit" order="4.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" xlink:label="AccumulatedOtherComprehensiveIncomeLossNetOfTax" xlink:title="AccumulatedOtherComprehensiveIncomeLossNetOfTax"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="StockholdersEquity" xlink:to="AccumulatedOtherComprehensiveIncomeLossNetOfTax" xlink:title="calculation: StockholdersEquity to AccumulatedOtherComprehensiveIncomeLossNetOfTax" order="5.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_MinorityInterest" xlink:label="MinorityInterest" xlink:title="MinorityInterest"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" xlink:to="MinorityInterest" xlink:title="calculation: StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest to MinorityInterest" order="2.0" weight="1.0"/>
  </link:calculationLink>
  <link:calculationLink xlink:type="extended" xlink:role="http://www.wfscorp.com/role/StatementOfIncome">
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_ProfitLoss" xlink:label="ProfitLoss" xlink:title="ProfitLoss"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments" xlink:label="IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments" xlink:title="IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="ProfitLoss" xlink:to="IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments" xlink:title="calculation: ProfitLoss to IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments" use="optional" order="1.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_OperatingIncomeLoss" xlink:label="OperatingIncomeLoss" xlink:title="OperatingIncomeLoss"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments" xlink:to="OperatingIncomeLoss" xlink:title="calculation: IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments to OperatingIncomeLoss" order="1.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_GrossProfit" xlink:label="GrossProfit" xlink:title="GrossProfit"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="OperatingIncomeLoss" xlink:to="GrossProfit" xlink:title="calculation: OperatingIncomeLoss to GrossProfit" order="1.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_Revenues" xlink:label="Revenues" xlink:title="Revenues"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="GrossProfit" xlink:to="Revenues" xlink:title="calculation: GrossProfit to Revenues" use="optional" order="1.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_CostOfRevenue" xlink:label="CostOfRevenue" xlink:title="CostOfRevenue"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="GrossProfit" xlink:to="CostOfRevenue" xlink:title="calculation: GrossProfit to CostOfRevenue" use="optional" order="2.0" weight="-1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_OperatingExpenses" xlink:label="OperatingExpenses" xlink:title="OperatingExpenses"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="OperatingIncomeLoss" xlink:to="OperatingExpenses" xlink:title="calculation: OperatingIncomeLoss to OperatingExpenses" order="2.0" weight="-1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_LaborAndRelatedExpense" xlink:label="LaborAndRelatedExpense" xlink:title="LaborAndRelatedExpense"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="OperatingExpenses" xlink:to="LaborAndRelatedExpense" xlink:title="calculation: OperatingExpenses to LaborAndRelatedExpense" use="optional" order="1.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_ProvisionForDoubtfulAccounts" xlink:label="ProvisionForDoubtfulAccounts" xlink:title="ProvisionForDoubtfulAccounts"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="OperatingExpenses" xlink:to="ProvisionForDoubtfulAccounts" xlink:title="calculation: OperatingExpenses to ProvisionForDoubtfulAccounts" use="optional" order="2.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_GeneralAndAdministrativeExpense" xlink:label="GeneralAndAdministrativeExpense" xlink:title="GeneralAndAdministrativeExpense"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="OperatingExpenses" xlink:to="GeneralAndAdministrativeExpense" xlink:title="calculation: OperatingExpenses to GeneralAndAdministrativeExpense" use="optional" order="3.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_NonoperatingIncomeExpense" xlink:label="NonoperatingIncomeExpense" xlink:title="NonoperatingIncomeExpense"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments" xlink:to="NonoperatingIncomeExpense" xlink:title="calculation: IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments to NonoperatingIncomeExpense" use="optional" order="2.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="int-20110630.xsd#int_InterestIncomeExpenseAndOtherFinancialCostsNet" xlink:label="InterestIncomeExpenseAndOtherFinancialCostsNet" xlink:title="InterestIncomeExpenseAndOtherFinancialCostsNet"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="NonoperatingIncomeExpense" xlink:to="InterestIncomeExpenseAndOtherFinancialCostsNet" xlink:title="calculation: NonoperatingIncomeExpense to InterestIncomeExpenseAndOtherFinancialCostsNet" use="optional" order="1.0" weight="-1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_OtherNonoperatingIncomeExpense" xlink:label="OtherNonoperatingIncomeExpense" xlink:title="OtherNonoperatingIncomeExpense"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="NonoperatingIncomeExpense" xlink:to="OtherNonoperatingIncomeExpense" xlink:title="calculation: NonoperatingIncomeExpense to OtherNonoperatingIncomeExpense" use="optional" order="2.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_IncomeTaxExpenseBenefit" xlink:label="IncomeTaxExpenseBenefit" xlink:title="IncomeTaxExpenseBenefit"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="ProfitLoss" xlink:to="IncomeTaxExpenseBenefit" xlink:title="calculation: ProfitLoss to IncomeTaxExpenseBenefit" use="optional" order="2.0" weight="-1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_NetIncomeLoss" xlink:label="NetIncomeLoss" xlink:title="NetIncomeLoss"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="NetIncomeLoss" xlink:to="ProfitLoss" xlink:title="calculation: NetIncomeLoss to ProfitLoss" use="optional" order="1.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_NetIncomeLossAttributableToNoncontrollingInterest" xlink:label="NetIncomeLossAttributableToNoncontrollingInterest" xlink:title="NetIncomeLossAttributableToNoncontrollingInterest"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="NetIncomeLoss" xlink:to="NetIncomeLossAttributableToNoncontrollingInterest" xlink:title="calculation: NetIncomeLoss to NetIncomeLossAttributableToNoncontrollingInterest" use="optional" order="2.0" weight="-1.0"/>
  </link:calculationLink>
  <link:calculationLink xlink:type="extended" xlink:role="http://www.wfscorp.com/role/StatementsOfShareholdersEquityAndComprehensiveIncome">
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_StockholdersEquityPeriodIncreaseDecrease" xlink:label="StockholdersEquityPeriodIncreaseDecrease" xlink:title="StockholdersEquityPeriodIncreaseDecrease"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_ProfitLoss" xlink:label="ProfitLoss" xlink:title="ProfitLoss"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="StockholdersEquityPeriodIncreaseDecrease" xlink:to="ProfitLoss" xlink:title="calculation: StockholdersEquityPeriodIncreaseDecrease to ProfitLoss" use="optional" order="1.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossArisingDuringPeriodNetOfTax" xlink:label="OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossArisingDuringPeriodNetOfTax" xlink:title="OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossArisingDuringPeriodNetOfTax"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="StockholdersEquityPeriodIncreaseDecrease" xlink:to="OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossArisingDuringPeriodNetOfTax" xlink:title="calculation: StockholdersEquityPeriodIncreaseDecrease to OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossArisingDuringPeriodNetOfTax" use="optional" order="2.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="int-20110630.xsd#int_InitialNoncontrollingInterestUponConsolidationOfJointVenture" xlink:label="InitialNoncontrollingInterestUponConsolidationOfJointVenture" xlink:title="InitialNoncontrollingInterestUponConsolidationOfJointVenture"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="StockholdersEquityPeriodIncreaseDecrease" xlink:to="InitialNoncontrollingInterestUponConsolidationOfJointVenture" xlink:title="calculation: StockholdersEquityPeriodIncreaseDecrease to InitialNoncontrollingInterestUponConsolidationOfJointVenture" use="optional" order="3.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_DividendsCash" xlink:label="DividendsCash" xlink:title="DividendsCash"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="StockholdersEquityPeriodIncreaseDecrease" xlink:to="DividendsCash" xlink:title="calculation: StockholdersEquityPeriodIncreaseDecrease to DividendsCash" use="optional" order="5.0" weight="-1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue" xlink:label="AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue" xlink:title="AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="StockholdersEquityPeriodIncreaseDecrease" xlink:to="AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue" xlink:title="calculation: StockholdersEquityPeriodIncreaseDecrease to AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue" use="optional" order="6.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation" xlink:label="StockIssuedDuringPeriodValueShareBasedCompensation" xlink:title="StockIssuedDuringPeriodValueShareBasedCompensation"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="StockholdersEquityPeriodIncreaseDecrease" xlink:to="StockIssuedDuringPeriodValueShareBasedCompensation" xlink:title="calculation: StockholdersEquityPeriodIncreaseDecrease to StockIssuedDuringPeriodValueShareBasedCompensation" use="optional" order="7.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueAcquisitions" xlink:label="StockIssuedDuringPeriodValueAcquisitions" xlink:title="StockIssuedDuringPeriodValueAcquisitions"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="StockholdersEquityPeriodIncreaseDecrease" xlink:to="StockIssuedDuringPeriodValueAcquisitions" xlink:title="calculation: StockholdersEquityPeriodIncreaseDecrease to StockIssuedDuringPeriodValueAcquisitions" use="optional" order="8.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="int-20110630.xsd#int_ShareRepurchasesRelatedToEmployeeStockBasedCompensationAwardsValue" xlink:label="ShareRepurchasesRelatedToEmployeeStockBasedCompensationAwardsValue" xlink:title="ShareRepurchasesRelatedToEmployeeStockBasedCompensationAwardsValue"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="StockholdersEquityPeriodIncreaseDecrease" xlink:to="ShareRepurchasesRelatedToEmployeeStockBasedCompensationAwardsValue" xlink:title="calculation: StockholdersEquityPeriodIncreaseDecrease to ShareRepurchasesRelatedToEmployeeStockBasedCompensationAwardsValue" use="optional" order="9.0" weight="-1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_MinorityInterestIncreaseFromStockIssuance" xlink:label="MinorityInterestIncreaseFromStockIssuance" xlink:title="MinorityInterestIncreaseFromStockIssuance"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="StockholdersEquityPeriodIncreaseDecrease" xlink:to="MinorityInterestIncreaseFromStockIssuance" xlink:title="calculation: StockholdersEquityPeriodIncreaseDecrease to MinorityInterestIncreaseFromStockIssuance" use="optional" order="4.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesPeriodIncreaseDecrease" xlink:label="StockIssuedDuringPeriodSharesPeriodIncreaseDecrease" xlink:title="StockIssuedDuringPeriodSharesPeriodIncreaseDecrease"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation" xlink:label="StockIssuedDuringPeriodSharesShareBasedCompensation" xlink:title="StockIssuedDuringPeriodSharesShareBasedCompensation"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="StockIssuedDuringPeriodSharesPeriodIncreaseDecrease" xlink:to="StockIssuedDuringPeriodSharesShareBasedCompensation" xlink:title="calculation: StockIssuedDuringPeriodSharesPeriodIncreaseDecrease to StockIssuedDuringPeriodSharesShareBasedCompensation" use="optional" order="1.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesAcquisitions" xlink:label="StockIssuedDuringPeriodSharesAcquisitions" xlink:title="StockIssuedDuringPeriodSharesAcquisitions"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="StockIssuedDuringPeriodSharesPeriodIncreaseDecrease" xlink:to="StockIssuedDuringPeriodSharesAcquisitions" xlink:title="calculation: StockIssuedDuringPeriodSharesPeriodIncreaseDecrease to StockIssuedDuringPeriodSharesAcquisitions" use="optional" order="2.0" weight="1.0"/>
    <link:loc xlink:type="locator" xlink:href="int-20110630.xsd#int_ShareRepurchasesRelatedToEmployeeStockBasedCompensationAwardsShares" xlink:label="ShareRepurchasesRelatedToEmployeeStockBasedCompensationAwardsShares" xlink:title="ShareRepurchasesRelatedToEmployeeStockBasedCompensationAwardsShares"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="StockIssuedDuringPeriodSharesPeriodIncreaseDecrease" xlink:to="ShareRepurchasesRelatedToEmployeeStockBasedCompensationAwardsShares" xlink:title="calculation: StockIssuedDuringPeriodSharesPeriodIncreaseDecrease to ShareRepurchasesRelatedToEmployeeStockBasedCompensationAwardsShares" use="optional" order="3.0" weight="-1.0"/>
  </link:calculationLink>
  <link:calculationLink xlink:type="extended" xlink:role="http://www.wfscorp.com/role/DisclosureDebtDetails">
    <link:loc xlink:type="locator" xlink:href="int-20110630.xsd#int_InterestIncomeExpenseAndOtherFinancialCostsNet" xlink:label="InterestIncomeExpenseAndOtherFinancialCostsNet" xlink:title="InterestIncomeExpenseAndOtherFinancialCostsNet"/>
    <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2011/elts/us-gaap-2011-01-31.xsd#us-gaap_InvestmentIncomeInterest" xlink:label="InvestmentIncomeInterest" xlink:title="InvestmentIncomeInterest"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="InterestIncomeExpenseAndOtherFinancialCostsNet" xlink:to="InvestmentIncomeInterest" xlink:title="calculation: InterestIncomeExpenseAndOtherFinancialCostsNet to InvestmentIncomeInterest" order="1.0" weight="-1.0"/>
    <link:loc xlink:type="locator" xlink:href="int-20110630.xsd#int_InterestExpenseAndOtherFinancialCostsNet" xlink:label="InterestExpenseAndOtherFinancialCostsNet" xlink:title="InterestExpenseAndOtherFinancialCostsNet"/>
    <link:calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="InterestIncomeExpenseAndOtherFinancialCostsNet" xlink:to="InterestExpenseAndOtherFinancialCostsNet" xlink:title="calculation: InterestIncomeExpenseAndOtherFinancialCostsNet to InterestExpenseAndOtherFinancialCostsNet" use="optional" order="2.0" weight="1.0"/>
  </link:calculationLink>
</link:linkbase>
