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Allowance For Doubtful Accounts For Trade Accounts Receivable
 6 Months Ended
Apr. 30, 2012
Allowance For Doubtful Accounts For Trade Accounts Receivable [Abstract]  
Allowance For Doubtful Accounts For Trade Accounts Receivable

(3) Allowance for Doubtful Accounts for Trade Accounts Receivable

A summary of changes in the allowance for doubtful accounts for trade accounts receivable for the six months ended April 30, 2012 and 2011 follows:

  Six Months Ended
  April 30,
  2012 2011
Balance at beginning of period $ 145,616   $ 120,450  
Bad debt expense (recovery)   13,947     (15,902 )
Losses charged to allowance   (30,411 )   (2,735 )
Balance at end of period $ 129,152   $ 101,813