Leitis, L. Ya.; Skolmeistere, R. A.; Golender, L. O.; Yansone, D. P.; Meksh, P. A.; Shimanskaya, M. V. Chemistry of Heterocyclic Compounds (New York, NY, United States), 1986 , vol. 22, # 1 p. 63 - 66 Khimiya Geterotsiklicheskikh Soedinenii, 1986 , vol. 22, # 1 p. 75 - 79