Patents.
3,445,660; 3,453,429; 3,453,432; 3,453,434; 3,457,412; 3,458,250; 3,487,213; 3,487,224; 3,488,101; 3,488,111; 3,488,118; 3,488,117; 3,489,482; 3,492,062; 3,492,063; 3,492,064; 3,492,493; 3,493,287; 3,493,288; 3,493,293; 3,493,768; 3,494,693; 3,495,189; 3,495,894; 3,495,892; 3,495,893; 3,495,895; 3,495,912; 3,496,429; 3,497,283; 3,497,284; 3,497,290; 3,497,291; 3,497,690; 3,497,704; 3,497,827; 3,497,828.