Patents.
3,187,093; 3,196,739; 3,205,775; 3,230,820; 3,283,645; 3,303,374; 3,386,333; 3,405,370; 3,406,292; 3,407,364; 3,408,498; 3,408,499; 3,408,593; 3,408,596; ; 3,410,999; 3,411,851; 3,416,865; 3,416,867; 3,418,036; 3,418,053; 3,418,483; 3,420,601; 3,421,002; 3,421,815; 3,421,820; 3,421,821; 3,423,588; 3,424,906; 3,426,194; 3,426,211; 3,427,090; 3,427,564; 3,427,567; 3,427,942; 3,428,401; 3,428,743; 3,428,811; 3,428,814; 3,429,636.