Gulevskaya, A. V.; Pozharskii, A. F.; Shvidchenko, S. V. Chemistry of Heterocyclic Compounds (New York, NY, United States), 1994 , vol. 30, # 9 p. 1087 - 1091 Khimiya Geterotsiklicheskikh Soedinenii, 1994 , vol. 9, p. 1253 - 1257