Drushlyak, A. G.; Ivashchenko, A. V.; Titov, V. V. Chemistry of Heterocyclic Compounds (New York, NY, United States), 1984 , vol. 20, # 10 p. 1155 - 1159 Khimiya Geterotsiklicheskikh Soedinenii, 1984 , vol. 20, # 10 p. 1399 - 1403