[1]
A. Davoodnia, “H2SO4/Silica gel: An Efficient and Reusable Heterogeneous Catalyst for the Synthesis of Pyrazolo[4,3-e][1,2,4]triazolo[4,3-c]pyrimidines”, ajc, vol. 22, no. 2, pp. 1595–1598, Mar. 2010.