Shubina, Yu. V.; Tikhomirov, D. A.; Eremeev, A. V. Chemistry of Heterocyclic Compounds (New York, NY, United States), 1985 , vol. 21, # 5 p. 516 - 520 Khimiya Geterotsiklicheskikh Soedinenii, 1985 , vol. 21, # 5 p. 618 - 622