Neiland, O. Ya.; Balodis, K. A.; Khodorkovskii, V. Yu.; Tilika, V. Zh. Chemistry of Heterocyclic Compounds (New York, NY, United States), 1991 , vol. 27, # 9 p. 1034 Khimiya Geterotsiklicheskikh Soedinenii, 1991 , # 9 p. 1278 - 1279