Karchava, A. V.; Maksimova, F. V.; Yurovskaya, M. A. Chemistry of Heterocyclic Compounds (New York, NY, United States), 1994 , vol. 30, # 10 p. 1195 - 1199 Khimiya Geterotsiklicheskikh Soedinenii, 1994 , # 10 p. 1378 - 1383