Barman, B., & Barua, S. (2010). Spectrophotometric Determination of Nickel(II) by Using Bis-[2,6-(2?-Hydroxy-4?-sulpho-1?-naphthylazo)]pyridine Disodium Salt. Asian Journal of Chemistry, 21(7), 5469–5474. Retrieved from https://asianpubs.org/index.php/ajchem/article/view/18335