Patents.
B 235,925; B 320,603; B 442,280; 3,861,784; 3,861,789; 3,864,030; 3,864,037; 3,865,490; 3,866,045; 3,868,499; 3,870,399; 3,870,400; 3,870,401; 3,870,402; 3,871,741; 3,871,748; 3,871,749; 3,871,772; 3,873,189.