Orlov, V. D.; Insuasti, B.; Desenko, S. M. Chemistry of Heterocyclic Compounds (New York, NY, United States), 1986 , vol. 22, # 5 p. 538 - 542 Khimiya Geterotsiklicheskikh Soedinenii, 1986 , vol. 22, # 5 p. 656 - 661