Shanazarov, A. K.; Kuzovkin, V. A.; Chistyakov, V. V.; Granik, V. G.
Chemistry of Heterocyclic Compounds (New York, NY, United States), 1991 , vol. 27, # 1 p. 71 - 76
Khimiya Geterotsiklicheskikh Soedinenii, 1991 , # 1 p. 86 - 92