1. S. B. Zhao, Ball-collector, Invention Patent No: CN200420032279. 3, (2005).
2. H. Chen, Y. Deng, C. H. Hu and G. Sun, Ping-pong Collector, Invention Patent No: CN200420031319. 2, (2005).
3. Y. P. Li, Ping-pong Facility Collector, Invention Patent No: CN200620130313, (2007).
4. X. P. Gao, Advanced Fluid Mechanics, 1st ed. Tianjin: Tianjin University Press, 2005, pp.1-5.
5. Y. Z. Wang, Vacuum Technology, 1st ed., Chengdu: Szechwan People Press, 1981, pp.11-19.