Doronina, S. O.; Gall', A. A.; Shishkin, G. V.
Chemistry of Heterocyclic Compounds (New York, NY, United States), 1992 , vol. 28, # 8 p. 917 - 920
Khimiya Geterotsiklicheskikh Soedinenii, 1992 , # 8 p. 1091 - 1094