Anisimova, V. A.; Levchenko, M. V. Chemistry of Heterocyclic Compounds (New York, NY, United States), 1987 , vol. 23, # 1 p. 48 - 52 Khimiya Geterotsiklicheskikh Soedinenii, 1987 , vol. 23, # 1 p. 59 - 63