Barman, Banjit, and Sudarsan Barua. 2010. “Bis-[2,6-(2’-Hydroxy-4’-Sulpho-1’-Naphthylazo)]pyridine Disodium Salt As a Spectrophotometric Reagent for the Determination of Cadmium in Tobacco and Tobacco Products”. Asian Journal of Chemistry 23 (2):770-72. https://asianpubs.org/index.php/ajchem/article/view/15834.