3VALENTINO James V, GOLDENBERG Joseph. Introduc- tion to Computer Numerical Control [ M ]. 3rd ed. Ken- dallville : Courier Kendallville Inc. ,2009:287 - 315.
4SMID Peter. CNC Programming Handbook:A Comprehehns- ive Guilde to Practical CNC Programming [ M ]. 2nd ed. New York : Industrial Press Inc. ,2008:484 - 500.