Barman, Banjit, and Sudarsan Barua. “Spectrophotometric Determination of Nickel(II) by Using Bis-[2,6-(2?-Hydroxy-4?-Sulpho-1?-naphthylazo)]pyridine Disodium Salt”. Asian Journal of Chemistry 21, no. 7 (March 30, 2010): 5469–5474. Accessed July 23, 2024. https://asianpubs.org/index.php/ajchem/article/view/18335.