Koty, Afraim, Mukul Sharma, Bindu Khare, and Ashutosh Srivastava. 2010. “Spectrophotometric Determination of Penicillamine With 2,6-Dichlorophenolindophenol in Drug Formulations”. Asian Journal of Chemistry 20 (6):4239-48. https://asianpubs.org/index.php/ajchem/article/view/19013.