参考文献

Ackermann, Jean; Brugger, Stephan; Conte, Aurelia; Hunziker, Daniel; Neidhart, Werner; Nettekoven, Matthias; Schulz-Gasch, Tanja; Wertheimer, Stanley Patent: US2011/92512 A1, 2011 ; Location in patent: Page/Page column 55 ;