| 1939 ASHTON Traffic Signaling System Patent |
| 1939 WILLY Projecting Means Submarine Signaling |
| 1939 DOWLING Railway Signaling System Patent |
| 1939 RYAN Railway Signaling Apparatus Patent |
| 1939 SUITS CHAUNCEY Submarine Signaling Patent |
| 1939 ATLAS Projecting Means Submarine Signaling |
| 1939 GEN ELECTRIC Submarine Signaling Patent |
| 1939 PFLASTERER Railway Signaling System Patent |
| 1939 VON VOIGTLANDER Sound Signaling Patent |
| 1939 UNION SWITCH SIGNAL CO Railway Signaling |
| 1939 HAKON Signaling Automobiles Art Print |
| 1939 DUDLEY HOMER Signaling System Patent Print |
| 1939 SCHWARZE ELECTRIC Sound Signaling Art |
| 1939 UNION SWITCH SIGNAL CO Railway Signaling System |
| 1939 ALLEN LAWRENCE Signaling Device Patent |
| 1939 DANIEL Animated Signaling Device Patent |
| 1939 UNION Approach Control Railway Signaling Systems |
| 1939 BELL TELEPHONE LABOR INC Signaling System |
| 1939 GRONDAHL Railway Signaling Apparatus Patent |
| 1939 ASSOCIATED Traffic Signaling System Art |
| 1939 BELL TELEPHONE LABOR INC Signaling Art |
| 1939 SHIELDS Approach Control Railway Signaling Systems |