RL Sharrah, PJ Ziegenfuss, MW Snyder - US Patent 7,652,216, 2010 - Google Patents
1,538,992 A 5/1925 Hopkins 2,530,913 A 11, 1950 Shackel 4,001,803 A 1/1977 Lombardo
4,074,122 A 2f1978 Moore 4,149,224. A 4/1979 King et al. 4,156,802 A 5, 1979 Gilano et al …