Shafiq, Muhammad, et al. “Synthesis and Antioxidant Activity of a New Series of 2,1-Benzothiazine 2,2-Dioxide Hydrazine Derivatives”. Asian Journal of Chemistry, vol. 24, no. 10, May 2012, pp. 4799-03, https://asianpubs.org/index.php/ajchem/article/view/9731.