Maksikova, A. V.; Serebryakova, E. S.; Tikhonova, L. G.; Vereshchagin, L. I. Chemistry of Heterocyclic Compounds (New York, NY, United States), 1980 , vol. 16, # 12 p. 1284 - 1285 Khimiya Geterotsiklicheskikh Soedinenii, 1980 , vol. 16, # 12 p. 1688 - 1689