Adwani, Purnima, et al. “A Single Step Synthesis of Substituted 3,7-Dimethyl-5-Nitro-4H-1,4-Benzothiazines ”. Asian Journal of Chemistry, vol. 5, no. 2, Mar. 2010, pp. 467-9, https://asianpubs.org/index.php/ajchem/article/view/24837.