Patents.
3,153,723; 3,260,880; 3,322,022; 3,354,309; 3,363,104; 3,370,503; 3,350,562; 3,372,969; 3,376,415; 3,378,685; 3,379,830; 3,381,129; 3,381,133; 3,381,134; 3,381,569; 3,381,570; 3,381,571; 3,381,572; 3,382,760; 3,383,508; 3,383,511; 3,383,512; 3,383,979; 3,384,752; 3,384,753; 3,384,754; 3,387,139; 3,387,534; 3,388,255; 3,388,259; 3,388,261; 3,388,262; 3,389,253; 3,389,265; 3,389,951; 3,389,952; 3,390,273; 3,390,604; 3,391,600; 3,391,278; 3,391,970; 3,391,972; 3,393,314; 3,393,603; 3,393,956; 3,394,253; 3,394,255; 3,394,257; 3,394,628; 3,394,630; 3,395,607; 3,395,608; 3,396,281; 3,396,301; 3,396,627; 3,396,343; 3,397,312; 3,398,285; 3,400,265; 3,400,267.