Patents.
3,932,744; 3,946,333; 3,976,360; 3,977,786; 3,998,552; 4,012,147; 4,014,614; 4,132,959; 4,132,962; 4,134,084; 4,135,167; 4,135,779; 4,136,317; 4,136,318; 4,136,568; 4,136,931; 4,137,509; 4,139,266; 4,139,267; 4,139,286; 4,141,651; 4,143,336; 4,143,337; 4,143,338; 4,143,339; 4,143,944; 4,143,945; 4,144,503; 4,145,115; 4,146,305; 4,158,505; 4,146,306; 4,162,832; 4,167,331; 4,168,113; 4,168,911; 4,169,660; 4,169,664; 4,169,001; 4,170,396; 4,170,402; 4,170,403; 4,170,416; 4,170,997; 4,171,159; 4,171,766; 4,171,864; 4,171,871; 4,171,872; 4,171,877; 4,171,880; 4,171,914; 4,171,915; 4,171,917; 4,172,156; 4,172,635; 4,172,636; 4,172,639; 4,172,994; 4,173,394; 4,173,395; 4,173,396; 4,173,399; 4,173,402; 4,174,151; 4,174,153;