1. Li Zhi-zhong, Pei Zhu-sen, Zhao Ru-xiong. Sorting machine fault diagnosis, recording and alarm devices[Z]. CN2306081, (1999).
2. HU Xiang dong, WANG Ping. Fault Diagnosis Expert System of Sorting Machine for Parcels and Printed Matter[J]. Journal of Chongqing University of Posts and Telecommunications, 2000, (03): 47-48.
3. LI Dian-sheng, SUN Wan-jun. Knowledge Processing Method of Fault Diagnosis Expert Systems for Letter Sorting Equipment[J]. The journal of China Universities of Posts and Telecommunications, 2001, 8(1): 42-46.
4. Gupta R. Survey on use of virtual environments in design and manufacturing. In: Proceedings of the 1996 ASME Design Engineering Technical Conferences and Computers in Engineering Conference, Irvine, California, August 18~22, (1996).
5. Heath M T, Dick W A. Virtual rocketry: rocket science meets computer science. IEEE Computational Science & Eng, 1998, 5(1~3): 16~26.