Patents.
5,082,350; 5,083,859; 5,089,023; 5,099,583; 5,100,230; 5,113,286; 5,166,508; 5,179,273; 5,202,689; 5,208,654; 5,216,236; 5,223,702; 5,223,910; 5,225,885; 5,225,893; 5,233,174; 5,237,388; 5,243,404; 5,247,343; 5,249,215; 5,256,885; 5,257,125; 5,257,132; 5,258,862; 5,260,826; 5,262,642; 5,262,646; 5,266,796; 5,267,015; 5,267,083; 5,270,528; 5,270,849; 5,270,853; 5,272,545; 5,272,568.