Patents.
3,361,030; 3,363,963; 3,364,066; 3,364,813; 3,365,295; 3,368,861; 3,370,904; 3,370,905; 3,371,213; 3,372,279; 3,373,059; 3,376,163; 3,380,793; 3,382,023; 3,384,434; 3,384,435; 3,243,588; 3,244,894; 3,244,921; 3,245,305; 3,245,309; 3,247,756; 3,249,480; 3,249,692; 3,251,937; 3,251,984; 3,256,767; 3,263,553; 3,343,972; 3,360,849; 3,361,025;