参考文献

Luithle, Joachim; Bob, Frank-Gerhard; Erb, Christina; Schnizler, Katrin; Flessner, Timo; Kampen, Marja van; Methfessel, Christoph Patent: US2007/37844 A1, 2007 ; Location in patent: Page/Page column 7 ; US 20070037844 A1