Tikhonova, L. G.; Serebryakova, E. S.; Maksikova, A. V.; Gareev, G. A.; Vereshchagin, L. I.
Chemistry of Heterocyclic Compounds (New York, NY, United States), 1981 , vol. 17, # 12 p. 1241 - 1244
Khimiya Geterotsiklicheskikh Soedinenii, 1981 , vol. 17, # 12 p. 1685 - 1688