1. German Patent 102004040314, 2007, Ref. Zh. Khim., 2007, 12-19N.136P.
2. USA Patent 5254645, 1993, C.A., 1994, vol. 120, no. 135492d.
3. USA Patent 5777144, 1998, C.A., 1998, vol. 129, no. 110026c.
4. USA Patent 5239099, 1993, C.A., 1994, vol. 119, no. 182668e.
5. USA Patent 5900315, 1999, Ref. Zh. Khim., 2000, 04-19N.207P.