Patents.
3,814,904; 3,817,606; 3,817,627; 3,824,017; 3,826,555; 3,829,193; 3,829,827; 3,832,026; 3,832,698; 3,833,281; 3,833,301; 3,834,785; 3,834,787; 3,860,327; 3,860,940; 3,862,794; 3,864,026; 3,864,027; 3,865,470; 3,867,018; 3,874,097; 3,874,771; 3,874,774; 3,876,875; 3,877,779; 3,877,792; 3,877,795; 3,877,796; 3,879,111; 3,879,113; 3,880,498; 3,880,501; 3,881,107; 3,881,812; 3,883,228; 3,883,229; 3,883,230; 3,883,231; 3,891,311; 3,898,584; 3,898,587; 3,900,802; 3,900,803; 3,902,137; 3,902,791; 3,902,793; 3,904,982; 3,904,983; 3,904,985; 3,905,686; 3,909,106; 3,909,523; 3,910,684; 3,910,685; B315,828; B425,035;