Rodinovskaya, L.A.; Sharanin, Yu.A.; Shestopalov, A.M.; Litvinov, V.P. Chemistry of Heterocyclic Compounds (New York, NY, United States), 1988 , p. 658 - 664 Khimiya Geterotsiklicheskikh Soedinenii, 1988 , vol. 24, # 6 p. 805 - 812