Drushlyak, A. G.; Ivashchenko, A. V.; Titov, V. V.
Chemistry of Heterocyclic Compounds (New York, NY, United States), 1984 , vol. 20, # 11 p. 1276 - 1280
Khimiya Geterotsiklicheskikh Soedinenii, 1984 , # 11 p. 1544 - 1548