Patents.
3,404,992; 3,409,429; 3,413,067; 3,414,345; 3,421,809; 3,413,460; 3,419,330; 3,433,555; 3,434,073; 3,434,779; 3,436,678; 3,437,942; 3,437,952; 3,442,566; 3,442,570; 3,443,243; 3,444,316; 3,446,561; 3,447,856; 3,448,284; 3,449,042; 3,449,053; 3,450,018; 3,450,469; 3,450,476; 3,450,478; 3,451,742; 3,451,755; 3,452,296; 3,452,657; 3,453,036; 3,453,037; 3,453,038; 3,453,043; 3,453,048; 3,453,106; 3,454,330; 3,453,442; 3,454,340; 3,454,341; 3,454,711; 3,454,768; 3,454,771; 3,454,778; 3,454,885; 3,455,622; 3,455,625; 3,455,627; 3,455,683; 3,456,998; 3,457,003; 3,457,071; 3,457,365; 3,457,419; 3,457,451; 3,458,244; 3,458,247; 3,458,249; 3,458,257; 3,458,259; 3,458,744; 3,458,829; 3,459,111; 3,460,882; 3,460,887; 3,461,856; 3,467,473; 3,472,593.