| 1937 HAY CLARENCE Signal Switch Patent Print Art |
| 1937 GEN RAILWAY SIGNAL CO Relay Patent Print |
| 1937 JOHNSON Railroad Crossing Signal Patent |
| 1937 WAGNER GEORGE Hotel Alarm Signal Patent |
| 1937 ELMER JOHNSON Warning Signal Patent Print |
| 1937 DAVIS MOORE Light Signal Patent Print Art |
| 1937 GODFREY GORT Traffic Signal Patent Print |
| 1937 KEITH JOHN Wigwag Signal Means Patent Print |
| 1937 GEN MOTORS CORP Sound Signal Patent Print |
| 1937 LEWIS Warning Signal Device Patent Print |
| 1937 SECO MFG COMPANY Wigwag Signal Means Patent |
| 1937 SUBMARINE SIGNAL CO Sound Producer Patent |
| 1937 SPARKS WITHINGTON CO Warning Signal Patent |
| 1937 CAMPBELL Pneumatic Signal System Patent |
| 1937 WILSON MERCER Crossing Signal Patent Print |
| 1937 GREGORY Railroad Crossing Signal Patent |
| 1937 PORTER Audible Signal Clock Patent Print |
| 1937 GEN ELECTRIC Signal System Patent Print Art |
| 1937 SUITS CHAUNCEY Signal System Patent Print |
| 1937 MOORE EDMUND Light Signal Unit Patent Print |