Tarshits, D. L.; Przhiyalgovskaya, N. M.; Suvorov, N. N.
Chemistry of Heterocyclic Compounds (New York, NY, United States), 1988 , vol. 24, # 11 p. 1217 - 1221
Khimiya Geterotsiklicheskikh Soedinenii, 1988 , vol. 24, # 11 p. 1472 - 1475