1. Z.J. Ye, M.H. Chen, R.S. Lu, Q. Yang and B. Yao, Rearch on wire bending technique, Forging & Stamping Technology, vol. 34, Apr. 2009, pp.121-123, doi: CNKI: SUN: DYJE. 0. 2009-02-044.
2. C.Z. Ma and B.H. Lu, Three dimensional design and modeling of helix syphon, Journal of Engineering Graphics, vol. 5, 2007, pp.29-32, doi: CNKI: SUN: GCTX. 0. 2007-05-006.
3. D.H. Cai, J.P. Gu and L.Q. Tu, Pipe bending simulated system based on OpenCASCADE, Light Industry Machinery, vol. 27, Feb. 2009, pp.36-38, doi: CNKI: SUN: QGJX. 0. 2009-01-020.
4. Y.M. Zhong, W.Y. Ma and B. Shirinzadeh, A methodology for solid modelling in a virtual reality environment, Robotics and Computer-Integrated Manufacturing, vol. 21, Dec. 2005, pp.528-549, doi: 10. 1016/j. rcim. 2004. 09. 003.
5. Department of Defense, Systems Management College: Systems Engineering Fundamentals, 2001, p.117.