Gorgos, V. I.; Zorin, L. M.; Zhungietu, G. I.; Rekhter, M. A. Chemistry of Heterocyclic Compounds (New York, NY, United States), 1983 , vol. 19, # 11 p. 1179 - 1181 Khimiya Geterotsiklicheskikh Soedinenii, 1983 , # 11 p. 1490 - 1492