参考文献:
Randolph, John T. Chen, Hui-Ju DeGoey, David A. Flentge, Charles A. Flosi, William J. Grampovnik, David J. Huang, Peggy P. Hutchinson, Douglas K. Kempf, Dale J. Klein, Larry L. Yeung, Ming C. Patent: US5/15969 A1, 5 Location in patent: Page/Page column 1 US 515969 A1