SUDHIR KUMAR, P., et al. “Synthesis of 3-Ethoxy Carbonyl 5-Phenyl-1- P-Tolyl 1,2,4-Triazolo [3,4,-C] 1,2,4-Triazole ”. Asian Journal of Chemistry, vol. 15, no. 1, Mar. 2010, pp. 515-8, https://asianpubs.org/index.php/ajchem/article/view/21618.