Lapachev, V. V.; Stekhova, S. A.; Mainagashev, I. Ya.; Fedotov, M. A.; Khall, V. E.; Mamaev, V. P. Chemistry of Heterocyclic Compounds (New York, NY, United States), 1986 , vol. 22, # 6 p. 633 - 639 Khimiya Geterotsiklicheskikh Soedinenii, 1986 , vol. 22, # 6 p. 802 - 809