Lokhande, R.S., and Rashmi N. Pawar. “Solvent Extraction and Spectrophotometric Determination of Co(II) With Isovanillin Thiosemicarbazone”. Asian Journal of Chemistry, vol. 18, no. 4, Mar. 2010, pp. 3241-3, https://asianpubs.org/index.php/ajchem/article/view/20827.