Kibina, I. Yu.; Musantaeva, Sh. M.; Shchelkunov, A. V. Chemistry of Heterocyclic Compounds (New York, NY, United States), 1987 , vol. 23, # 6 p. 636 - 637 Khimiya Geterotsiklicheskikh Soedinenii, 1987 , vol. 23, # 6 p. 770 - 771