Khrimyan, A. P.; Karapetyan, A. V.; Badanyan, Sh. O. Chemistry of Heterocyclic Compounds (New York, NY, United States), 1984 , vol. 20, # 2 p. 189 - 196 Khimiya Geterotsiklicheskikh Soedinenii, 1984 , vol. 20, # 2 p. 230 - 238