Mamedov, E. J.; Ismailov, A. G.; Kozhushkov, S. I.; Zefirov, N. S. Chemistry of Heterocyclic Compounds (New York, NY, United States), 1992 , vol. 28, # 3 p. 260 - 265 Khimiya Geterotsiklicheskikh Soedinenii, 1992 , # 3 p. 313 - 319