Shitole, B. V., N. V. Shitole, and G. K. Kakde. “Disodium Phosphate: A Highly Efficient Catalyst for One-Pot Synthesis of Substituted 3,4-Dihydropyrano[3,2-C]Chromenes”. Orbital: The Electronic Journal of Chemistry, Vol. 9, no. 3, July 2017, pp. 131-4, https://periodicos.ufms.br/index.php/orbital/article/view/16490.