Gevorkyan, A. A.; Kazaryan, P. I.; Avakyan, O. V.; Vardanyan, R. A.
Chemistry of Heterocyclic Compounds (New York, NY, United States), 1991 , vol. 27, # 1 p. 27 - 30
Khimiya Geterotsiklicheskikh Soedinenii, 1991 , # 1 p. 33 - 36