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Trade Accounts and Bills Receivable, net (Tables)
12 Months Ended
Dec. 31, 2018
Trade Accounts and Bills Receivable, net [Abstract]  
Schedule of trade accounts and bills receivable

   December 31,   December 31, 
   2017   2018 
Trade accounts receivable  $42,095,211   $19,054,863 
Less: Allowance for doubtful accounts   (3,700,922)   (3,657,173)
    38,394,289    15,397,690 
Bills receivable   19,124,323    6,353,342 
   $57,518,612   $21,751,032 

Schedule of analysis of the allowance for doubtful accounts
   December 31,   December 31, 
   2017   2018 
Balance at beginning of year  $2,761,144   $3,700,922 
Provision for the year   839,917    474,950 
Reversal - recoveries by cash   (114,542)   (312,462)
Charged to consolidated statements of operations and comprehensive (loss) income  $725,375   $162,488 
Foreign exchange adjustment   214,403    (206,237)
Balance at end of year  $3,700,922   $3,657,173