Solomko, Z. F.; Sheremet, V. I.; Khmel', M. P.; Avramenko, V. I.; Proshkina, V. N. Chemistry of Heterocyclic Compounds (New York, NY, United States), 1982 , vol. 18, # 3 p. 307 - 310 Khimiya Geterotsiklicheskikh Soedinenii, 1982 , vol. 18, # 3 p. 405 - 409