Patents.
3,136,208; 3,144,511; 3,148,582; 3,149,231; 3,155,828; 3,157,728; 3,157,788; 3,158,509; 3,161,772; 3,161,773; 3,163,699; 3,163,760; 3,164,663; 3,166,418; 3,166,673; 3,170,021; 3,170,022; 3,225,644; 3,238,373; 3,250,177; 3,251,261; 3,267,266; 3,282,148; 3,285,124; 3,286,097; 3,297,873; 3,306,156; 3,307,448; 3,312,143; 3,312,144; 3,312,547; 3,313,937; 3,313,938; 3,313,941; 3,314,327; 3,314,816; 3,315,075; 3,316,050; 3,317,266; 3,317,315; 3,317,662; 3,317,732; 3,319,065; 3,319, 071; 3,319,514; 3,322,482; 3,322,485; 3,322,487; 3,324,295; 3,324,296; 3,324,303; 3,325,241; 3,326,619; 3,327,120; 3,327,583.