Knyazeva, V. F.; Granik, V. G.; Glushkov, R. G.; Solov'eva, N. P.; Anisimova, O. S. Chemistry of Heterocyclic Compounds (New York, NY, United States), 1981 , p. 370 - 374 Khimiya Geterotsiklicheskikh Soedinenii, 1981 , vol. 17, # 4 p. 511 - 515