Sharma, Kavita, et al. “Use of 3-Hydroxy-M-Toylol-1-O-Chlorophenyltriazene in the Spectrophotometric Determination of Copper(II)”. Asian Journal of Chemistry, vol. 11, no. 3, Mar. 2010, pp. 1069-70, https://asianpubs.org/index.php/ajchem/article/view/23434.