Patents.
3,407,294; 3,417,345; 3,418,599; 3,440,560; 3,495,890; 3,496,483; 3,440,561; 3,497,289; 3,503,674; 3,504,957; 3,504,959; 3,504,961; 3,506,327; 3,506,332; 3,506,333; 3,506,336; 3,506,337; 3,506,339; 3,506,340; 3,506,359; 3,506,361; 3,506,928; 3,507,547; 3,507,549; 3,507,553; 3,507,554; 3,507,555; 3,507,558; 3,507,559; 3,507,560; 3,507,564; 3,508,810; 3,508,808; 3,508,809; 3,508,811; 3,508,829; 3,508,830; 3,510,191; 3,510,198; 3,510,199; 3,510,200; 3,510,203; 3,510,224; 3,510,226; 3,511,992; 3,511,554; 3,511,556; 3,511,928; 3,512,869; 3,512,871; 3,512,889; 3,512,891; 3,512,895; 3,514,174; 3,514,175; 3,514,176; 3,514,186; 3,514,187; 3,515,452; 3,515,458; 3,515,459; 3,515,460; 3,515,464; 3,515,480; 3,516,734; 3,517,980; 3,517,983; 3,518,002; 3,519,354; 3,519,355; 3,520,617;