Kirpichenok, M. A.; Mel'nikova, L. M.; Denisov, L. K.; Grandberg, I. I. Chemistry of Heterocyclic Compounds (New York, NY, United States), 1988 , vol. 24, # 9 p. 959 - 965 Khimiya Geterotsiklicheskikh Soedinenii, 1988 , # 9 p. 1169 - 1175