Lobanov, P. S.; Grebelkin, A. L.; Zaitsev, D. I.; Gindin, V. A.; Potekhin, A. A. Chemistry of Heterocyclic Compounds (New York, NY, United States), 1991 , vol. 27, # 10 p. 1116 - 1119 Khimiya Geterotsiklicheskikh Soedinenii, 1991 , vol. 27, # 10 p. 1388 - 1391