Patents.
3,868,173; 3,868,174; 3,871,741; 3,889,208; 3,894,789; 3,916,338; 3,934,211; 3,936,155; 3,936,772; 3,938,172; 3,940,713; 3,942,132; 3,946,334; 3,949,319; 3,969,016; 3,969,573; 3,974,376; 3,977,767; 3,977,018; 3,977,793; 3,978,458; 3,980,390; 3,980,392; 3,980,395; 3,981,591; 3,982,816; 3,982,818; 3,982,833; 3,990,770; 3,992,081; 3,992,083; 3,992,084; 3,992,623; 3,994,573; 3,994,576; 3,998,528; 3,998,529; 4,001,840; 4,002,406; 4,002,407; 4,005,285; 4,009,934; 4,009,938; 4,009,945; 4,009,956; 4,013,347; 4,014,608; 4,015,896; 4,015,897; 4,017,147; 4,017,148; 4,017,163; 4,017,171; 4,018,509; 4,018,512; 4,018,523; 4,019,157; 4,021,099; 4,025,157; 4,025,199; 4,025,783; 4,027,951; 4,027,952; 4,027,976; 4,028,544; 4,028,548; 4,028,719; 4,029,396; 4,029,419; 4,030,805; 4,033,052; 4,033,667; 4,033,674; 4,033,688; 4,037,934; 4,040,039; 4,040,056; 4,040,720; 4,042,295; 4,045,127; 4,045,128; 4,046,459; 4,046,460; 4,048,587; 4,050,778; 4,050,779; 4,052,121; 4,054,369; 4,055,378; 4,056,306; 4,056,310; 4,056,311; 4,057,328; 4,057,330; 4,059,340; 4,059,342; 4,059,344; 4,059,348; 4,060,306; 4,060,312; 4,061,418.