Drevko, B. I.; Smushkin, M. I.; Fomenko, L. A.; Kharchenko, V. G. Chemistry of Heterocyclic Compounds (New York, NY, United States), 1995 , vol. 31, # 1 p. 20 - 22 Khimiya Geterotsiklicheskikh Soedinenii, 1995 , # 1 p. 24 - 26