Bubel', O. N.; Tishchenko, I. G.; Grinkevich, O. A. Chemistry of Heterocyclic Compounds (New York, NY, United States), 1985 , vol. 21, # 12 p. 1335 - 1338 Khimiya Geterotsiklicheskikh Soedinenii, 1985 , vol. 21, # 12 p. 1624 - 1628