1. Andreev, V.P., Ryzhakov, A.V., Morozov, A.K., Alekseeva, O.O., and Rodina, L.L., Khim. Geterotsikl. Soedin., 1995, no. 6, p. 760.
2. Ochiai, E., J. Org. Chem., 1953, vol. 18, no.5, p. 534.
3. Andreev, V.P. and Ryzhakov, A.V., Khim. Geterotsikl. Soedin., 1993, no. 12, p. 1662.
4. Dega-Szafran, Z. and Szafran, M., Heterocycles, 1994, vol. 37, no.1, p. 627.
5. Rabinovich, V.A. and Khavin, Z.Ya., Kratkii khimicheskii spravochnik (Concise Chemical Handbook), Leningrad: Khimiya, 1978, pp. 334–338.