| 1928 FRANK Rail Crossing Signal Patent Print Art |
| 1928 DELCO REMY CORP Sound Signal Patent Print |
| 1928 FRANCIS Signal Art Print |
| 1928 CLARK COOPER Pneumatic Signal Patent Print |
| 1928 ADLAKE CO Signal Lantern Patent Print Art |
| 1928 SPARKS WITHINGTON CO Signal Patent Print |
| 1928 WIDMYER ROBERT Signal Device Patent Print |
| 1928 MILLER CHARLES Railway Signal Patent Print |
| 1928 BRADLEY Theft Signal Switch Patent Print |
| 1928 STEVENS JOHN Signal Patent Print Art |
| 1928 UNION SWITCH SIGNAL CO Decoding Art Print |
| 1928 WESTINGHOUSE AIR BRAKE CO Signal Art Print |
| 1928 HANSON Signal For Automobiles Patent Print |
| 1928 HAMM WILLIAM Signal Lantern Patent Print |
| 1928 WILLIAM Signal Art Print Patent |
| 1928 JOHN Traffic Signal Apparatus Patent Print |
| 1928 BRITTON HYBARGER Signal Device Patent Print |
| 1928 EWALD C DIECKERHOFF Signal Patent Print Art |
| 1928 GEN Block Signal System Railroads Art Print |
| 1928 SPEAR FURMAN Train Signal Lamp Patent Print |
| 1928 JENNINGS NELSON Signal System Patent Print |
| 1928 FRANCIS HOGG Signal Device Patent Print Art |