1. D. W. Zuo, S.L. Song et al: Key Engineering Material Vol. 258-259 (2004), p.517.
2. G.H. Li, F.X. Lu et al : Chinese Patent CN1099547A.
3. T.B. Huang, J.M. Liu, et al: Journal of University of Science and Technology Vol. 22 (2000) No. 5, p.467.
4. S.L. Song, D.W. Zuo et al: Journal of Applied Science Vol. 21 (2003) No. 4, p.423.
5. H.Q. Li, G.F. Zhong et al: Journal of University of Science and Technology Vol. 16 (1994) No. 6, p.547.