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Trade Accounts and Bills Receivable, Net (Tables)
12 Months Ended
Dec. 31, 2019
Trade Accounts and Bills Receivable, net [Abstract]  
Schedule of trade accounts and bills receivable
  December 31,   December 31, 
   2018   2019 
Trade accounts receivable  $19,054,863   $12,517,626 
Less: Allowance for doubtful accounts   (3,657,173)   (4,650,686)
    15,397,690    7,866,940 
Bills receivable   6,353,342    85,480 
   $21,751,032   $7,952,420 
Schedule of analysis of the allowance for doubtful accounts

   December 31,   December 31, 
   2018   2019 
Balance at beginning of year  $3,700,922   $3,657,173 
Provision for the year   474,950    1,613,402 
Reversal - recoveries by cash   (312,462)   (567,042)
Charged to consolidated statements of operations and comprehensive (loss) income  $162,488   $1,046,360 
Foreign exchange adjustment   (206,237)   (52,847)
Balance at end of year  $3,657,173   $4,650,686