Novikova, A. P.; Perova, N. M.; Egorova, L. G.; Bragina, E. I. Chemistry of Heterocyclic Compounds (New York, NY, United States), 1991 , vol. 27, # 6 p. 666 - 668 Khimiya Geterotsiklicheskikh Soedinenii, 1991 , vol. 27, # 6 p. 843 - 846