Lokhande, R.S., and A.S. Jaywant. “Extractive Spectrophotometric Determination of Copper With P-Methylisonitrosoacetophenonehydrazone”. Asian Journal of Chemistry, vol. 11, no. 3, Mar. 2010, pp. 1040-2, https://asianpubs.org/index.php/ajchem/article/view/23423.