| 1924 WESTERN ELECTRIC CO Signaling System Patent |
| 1931 WESTERN ELECTRIC CO Signaling Device Patent |
| 1931 BUTLER Electric Signaling Apparatus Patent |
| 1923 SIEMENS AG Electric Signaling System Patent |
| 1921 WESTERN ELECTRIC CO Signaling System Patent |
| 1932 SCHWARZE ELECTRIC COMPANY Signaling Patent |
| 1937 NELSON Electric Signaling System Patent |
| 1920 ROOT Electric Signaling Device Patent Print |
| 1923 PAUL Electric Signaling System Patent Print |
| 1934 PLACE Electric Signaling System Patent |
| 1939 GEN ELECTRIC Submarine Signaling Patent |
| 1953 FRANK Electric Signaling Device Patent |
| 1944 FISH Electric Signaling Apparatus Patent |
| 1962 WEBER Electric Signaling Device Patent |
| 1948 ANDREW Electric Signaling System Patent |
| 1926 Electric Signaling System Patent Print Art |
| 1926 HERMANN Electric Signaling System Patent |
| 1926 SIEMENS AG Electric Signaling System Patent |
| 1934 LOEFFLER Electric Signaling Device Patent |
| 1933 LOEFFLER Electric Signaling Device Patent |