N. Gautam, M. Sharma, V. Gautam, M. Sharma, and D. Gautam, “Synthesis, Spectral Characterization and Antioxidative Evaluation of Substituted 4H-1,4-Benzothiazine and Their Sulfones”, ajc, vol. 22, no. 7, pp. 5380–5388, Jun. 2010.