Minbaev, B. U.; Shostakovskii, M. F.; Kagarlitskii, A. D. Chemistry of Heterocyclic Compounds (New York, NY, United States), 1983 , vol. 19, # 9 p. 957 - 959 Khimiya Geterotsiklicheskikh Soedinenii, 1983 , # 9 p. 1199 - 1200