Vigante, B. A.; Ozols, Ya. Ya.; Dubur, G. Ya.; Beilis, Yu. I.; Belash, E. M.; Prezhdo, V. V. Chemistry of Heterocyclic Compounds (New York, NY, United States), 1982 , vol. 18, # 2 p. 170 - 178 Khimiya Geterotsiklicheskikh Soedinenii, 1982 , vol. 18, # 2 p. 219 - 228