| 1938 UNION SWITCH SIGNAL CO Railway Signaling |
| 1938 PRESTON Signaling System For Railroads Art |
| 1938 WILLING Highway Crossing Signaling System |
| 1938 UNION SWITCH SIGNAL CO Railway Signaling System |
| 1938 MACKEY Highway Crossing Signaling System |
| 1938 PFLASTERER Railway Signaling System Patent |
| 1938 LAY CHARLES Railway Signaling Patent Print |
| 1938 CRAGO PAUL Railway Signaling Patent Print |
| 1938 GEN RAILWAY SIGNAL CO Railway Signaling System |
| 1938 MCCANN RONALD Railway Signaling Patent |
| 1938 CRAGO PAUL Signaling Apparatus Patent Print |
| 1938 BAUGHMAN Railway Signaling Apparatus Patent |
| 1938 RADIO Signaling System Railway Installations |
| 1938 PFLASTERER Railway Signaling Patent Print |
| 1938 JUDGE Railway Signaling System Patent Print |
| 1938 REICHARD Highway Crossing Signaling System |
| 1938 MCDONALD Automatic Train Control Signaling System |
| 1938 UNION SWITCH SIGNAL CO Signaling Art Print |
| 1938 WILLING Signaling System For Railroads Art |
| 1938 GEN Highway Crossing Signaling System Art |
| 1938 THOMPSON Railway Signaling Patent Print Art |
| 1938 FIELD Highway Crossing Signaling System Art |
| 1938 GEN RAILWAY SIGNAL CO Signaling System Railroads |
| 1938 PAUL Signaling System Railway Installations |
| 1938 KEMMERER Railway Signaling Patent Print Art |
| 1938 PFLASTERER Railway Signaling Apparatus Art |
| 1938 RICHARDS Train Signaling System Patent |
| 1938 GRAY Signaling System Same Art Print Patent |