参考文献

Grimm, Erich L.; Ducharme, Yves; Frenette, Richard; Friesen, Richard; Gagnon, Marc; Juteau, Helene; Laliberte, Sebastien; MacKay, Bruce; Gareau, Yves Patent: US2008/188521 A1, 2008 ; Location in patent: Page/Page column 12 ;