1. D. A. Maiboroda and E. V. Babaev, Khim. Geterotsikl. Soedin., 1445 (1995). [Chem. Heterocycl. Comp., 31, 1251 (1995)].
2. H. C. van der Plas, in: A. R. Katritzky (editor), Advances in Heterocyclic Chemistry, Vol. 74, Academic Press, San Diego, London, Boston, New York, Sydney, Tokyo, Toronto (1999), p. 155.
3. E. S. H. El Ashry, Y. El Kilany, N. Rashed, and H. Assafir, in: A. R. Katritzky (editor), Advances in Heterocyclic Chemistry, Vol. 75, Academic Press, San Diego, London, Boston, New York, Sydney, Tokyo, Toronto (1999), p. 79.
4. V. V. Didenko, Kh. S. Shikhaliev, and I. V. Ledenyova, Khim. Geterotsikl. Soedin., 307 (2009). [Chem. Heterocycl. Comp., 45, 248 (2009)].
5. Kh. S. Shikhaliev, V. V. Didenko, V. A. Voronkova, and D. V. Kryl’skii, Izv. Akad. Nauk, Ser. Khim., 1008 (2009).