Bakherad, Mohammad, Amir H Amin, and Rahele Doosti. “Caffeine As A Catalyst for A Four-Component Synthesis of Dihydropyrano [2, 3-C]Pyrazoles in Water”. To Chemistry Journal 2 (April 17, 2019): 154-164. Accessed July 6, 2020. https://purkh.com/index.php/tochem/article/view/372.