Shakhgel'diev, M. A.; Babaeva, G. B.; Nabiev, O. G.; Kostyanovskii, R. G. Chemistry of Heterocyclic Compounds (New York, NY, United States), 1987 , vol. 23, # 5 p. 592 Khimiya Geterotsiklicheskikh Soedinenii, 1987 , vol. 23, # 5 p. 712