Ryabukhin, Yu. I.; Eliseeva, A. Yu.; Suzdalev, K. F.; Bulgarevich, S. B.; Movshovich, D. Ya.; et al. Chemistry of Heterocyclic Compounds (New York, NY, United States), 1992 , vol. 28, # 4 p. 454 - 463 Khimiya Geterotsiklicheskikh Soedinenii, 1992 , # 4 p. 540 - 549