Luk'yanenko, N. G.; Bogat-skii, A. V.; Popkov, Yu. A. Chemistry of Heterocyclic Compounds (New York, NY, United States), 1980 , vol. 16, # 3 p. 222 - 225 Khimiya Geterotsiklicheskikh Soedinenii, 1980 , vol. 16, # 3 p. 306 - 309