Krivopalov, V. P.; Nikolaenkova, E. B.; Sedova, V. F.; Mamaev, V. P. Chemistry of Heterocyclic Compounds (New York, NY, United States), 1983 , vol. 19, # 9 p. 977 - 981 Khimiya Geterotsiklicheskikh Soedinenii, 1983 , # 9 p. 1222 - 1226