Savel'ev, V. L.; Artamonova, O. S.; Troitskaya, V. S.; Shaviryna, V. V.; Afanas'eva, T. G.; Zagorevskii, V. A. Chemistry of Heterocyclic Compounds (New York, NY, United States), 1982 , vol. 18, # 7 p. 676 - 679 Khimiya Geterotsiklicheskikh Soedinenii, 1982 , # 7 p. 896 - 899