Semeikin, A. S.; Koifman, O. I.; Berezin, B. D. Chemistry of Heterocyclic Compounds (New York, NY, United States), 1982 , vol. 18, # 10 p. 1046 - 1047 Khimiya Geterotsiklicheskikh Soedinenii, 1982 , vol. 18, # 10 p. 1354 - 1355