Kartsev, V.G.; Chapyshev, S.V.; Sipyagin, A.M.; Yashina, N.S.; Petrosyan, V.S. Chemistry of Heterocyclic Compounds (New York, NY, United States), 1983 , vol. 19, p. 886 - 889 Khimiya Geterotsiklicheskikh Soedinenii, 1983 , vol. 19, # 8 p. 1103 - 1107