Shvekhgeimer, G. A.; Kelarev, V. I.; Dyankova, L. A. Chemistry of Heterocyclic Compounds (New York, NY, United States), 1984 , vol. 20, # 12 p. 1324 - 1330 Khimiya Geterotsiklicheskikh Soedinenii, 1984 , # 12 p. 1609 - 1615