Patents.
3,145,247; 3,153,689; 3,156,755; 3,157,726; 3,164,058; 3,165,586; 3,175,458; 3,175,460; 3,229,101; 3,229,102; 3,241,430; 3,258,599; 3,263,088; 3,288,021; 3,296,921; 3,306,159; 3,307,446; 3,307,449; 3,310,700; 3,311,441; 3,315,078; 3,315,560; 3,315,563; 3,316,053; 3,316,410; 3,316,803; 3,316,805; 3,317,730; 3,317,735; 3,317,738; 3,319,097; 3,320,019; 3,320,429; 3,321,659; 3,321,660; 3,322,953; 3,323,010; 3,324,326; 3,324,327; 3,325,665; 3,325,666; 3,326,076; 3,326,077; 3,326,624; 3,326,715; 3,328,584; 3,329,813; 3,329,823; 3,330,615; 3,330,692; 3,333,106; 3,334,542; 3,334,959; 3,336,095; 3,336,096; 3,341,705; 3,342,540.