Patents.
3,567,948; 3,610,023; 3,610,734; 3,610,754; 3,614,194; 3,614,212; 3,623,789; 3,651,322; 3,653,743; 3,655,266; 3,653,744; 3,655,267; 3,655,379; 3,656,019; 3,656,835; 3,656,836; 3,658,423; 3,658,424; 3,663,087; 3,663,088; 3,663,092; 3,663,094; 3,663,813; 3,663,822; 3,663,893; 3,666,358; 3,666,941; 3,666,943; 3,667,828; 3,668,546; 3,669,527; 3,669,529; 3,669,547; 3,670,258; 3,671,098; 3,671,104; 3,671,122; 3,671,130; 3,672,746; 3,672,747; 3,672,748; 3,672,776; 3,673,327; 3,674,330; 3,674,333; 3,674,334; 3,674,335;