Nasakin, O.E.; Alekseev, V.V.; Terent'ev, P.B.; Bulai, A.Kh.; Zablotskaya, M.Yu. Chemistry of Heterocyclic Compounds (New York, NY, United States), 1983 , p. 851 - 854 Khimiya Geterotsiklicheskikh Soedinenii, 1983 , vol. 19, # 8 p. 1062 - 1066