1. D. R. Lee and L. K. Marie: EP patent, 822, 185(1998).
2. C. Liang: Fine and Speciality Chemicals, (2002), p.6( In Chinese).
3. N. N. Suvorov, V. G. Avramenko, v. N. Shkilkova, et al: U.S. Patent, 1, 174, 034, (1968).
4. H. Hayshi, K. Kurokawa, W. Hosokawa, et al: Journal of Catalysis, Vol. 66(1980), p.49.
5. N. N. Suvorov, V. G. Avramenko, V. G. Shkilkova, et al: FR patent, 1, 562, 253(1969).