参考文献:
Barvian, Kevin K Carpenter, Andrew J Cooper, Joel P Feldman, Paul L Garrido, Dulce M Guo, Yu C Handlon, Anthony L Hertzog, Donald L Hyman, Clifton E Peat, Andrew J Peckham, Gregory E Speake, Jason D Swain, William R Tavares, Francis X Zhou, Huiqiang J Patent: US6/19871 A1, 6 Location in patent: Page/Page column 31 US 619871 A1