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Trade Accounts and Bills Receivable, Net (Tables)
9 Months Ended
Sep. 30, 2020
Trade Accounts and Bills Receivable, net [Abstract]  
Schedule of trade accounts and bills receivable
   December 31,   September 30, 
   2019   2020 
Trade accounts receivable  $12,517,626   $23,664,220 
Less: Allowance for doubtful accounts   (4,650,686)   (4,834,640)
    7,866,940    18,829,580 
Bills receivable   85,480    252 
   $7,952,420   $18,829,832 
Schedule of analysis of the allowance for doubtful accounts
   September 30,   September 30, 
   2019   2020 
Balance at beginning of period  $3,657,173   $4,650,686 
Provision for the period   735,619    981,241 
Reversal - recoveries by cash   (292,599)   (917,707)
Charged to consolidated statements of operations and comprehensive (loss) income   443,020    63,534 
Foreign exchange adjustment   (156,210)   120,420 
Balance at end of period  $3,943,983   $4,834,640