Patents.
3,784,791; 3,785,262; 3,785,265; 3,786,180; 3,786,238; 3,790,284; 3,792,915; 3,794,406; 3,796,476; 3,796,494; 3,796,887; 3,797,907; 3,797,910; 3,797,922; 3,799,653; 3,799,654; 3,800,149; 3,801,181; 3,801,188.