Butt, M., R. KEMAL, A. SALAM, and A. AKHTAR. “?SYNTHESIS OF HETERO-BICYCLIC COMPOUNDS Part-IX. Formation of 2,2-Disubstituted 4,5-Dioxo-Pyridino [4,3-D] [1,3]dioxins”. Biological Sciences - PJSIR, vol. 40, no. 5-12, Oct. 1997, pp. 1-4, https://v2.pjsir.org/index.php/biological-sciences/article/view/2339.