1. Y.W. Liu, L.B. Liu and X.S. Zhao: China Mechanical Engineering, Vol. 9 (1998) No. 12, pp.48-52.
2. J.A. Soons and F.C. Theuws: Precision Engineering Vol. 14 (1992) No. 1, p.5219.
3. Y.W. Liu: China Mechanical Engineering Vol. 11 (2000) No. 1, pp.144-149.
4. ASME B5. 54-1992, an American ational Standard, by the American Society of Mechanical Engineers (1992).
5. ISO 230-6: 2002, an International Standard, by International Standards Organization(2002).