Patents.
4,408,329; 4,439,860; 4,447,723; 4,453,163; 4,458,977; 4,458,978; 4,458,981; 4,458,991; 4,460,240; 4,460,251; 4,461,283; 4,461,533; 4,461,541; 4,461,546; 4,462,658; 4,462,660; 4,462,662; 4,462,663; 4,462,664; 4,462,687; 4,464,022; 4,464,023; 4,464,024; 4,464,051; 4,465,333; 4,465,334; 4,465,342; 4,465,343; 4,465,345; 4,465,347; 4,466,693; 4,466,694; 4,466,699; 4,466,707; 4,466,708; 4,466,710; 4,466,711; 4,467,334; 4,468,096; 4,468,097; 4,468,098; 4,468,099; 4,468,100; 4,469,396; 4,469,407; 4,469,412; 4,469,941.