参考文献:
Walker, Daniel Patrick Piotrowski, David W. Jacobsen, Eric Jon Acker, Brad A. Groppi JR., Vincent E. Patent: US003/3853 A, 003 Location in patent: Page 38
参考文献:
Wishka, Donn G. Walker, Daniel Patrick Corbett, Jeffrey W. Reitz, Steven Charles Rauckhorst, Mark R. Groppi JR., Vincent E. Patent: US003/05089 A, 003 US 003005089 A