M. Nadeem Arshad, I. Ullah Khan, M. Zia-Ur-Rehman, and M. Shafiq, “Antioxidant Potential of New Methyl-4-hydroxy-2H- 1,2-benzothiazine-3-carboxylate-1,1-dioxide Derivatives”, ajc, vol. 23, no. 6, pp. 2801–2805, Mar. 2011.