Remennikov, G. Ya.; Boldyrev, I. V.; Kravchenko, S. A.; Pirozhenko, V. V. Chemistry of Heterocyclic Compounds (New York, NY, United States), 1993 , vol. 29, # 10 p. 1200 - 1205 Khimiya Geterotsiklicheskikh Soedinenii, 1993 , # 10 p. 1398 - 1404