DM Sprague, DA Brendes - US Patent 7,046,667, 2006 - Google Patents
5,586, 177 A 12/1996 Farris et al. 6,111,893 A 8/2000 Volftsun et al. 5,638,431 A 6, 1997
Everett et al. 6,112,090 A 8, 2000 Valentine 5,640,446 A 6, 1997 Everett et al. 6,115,383 A 9 …