| 1931 WALDEN HAROLD Game Apparatus Patent Print |
| 1931 RICHARDS Signaling Apparatus Patent Print |
| 1931 LA RIZZA Amusement Apparatus Patent Print |
| 1931 BAHR Ship Raising Apparatus Patent Print |
| 1931 MEARS Speed Control Apparatus Patent Print |
| 1931 EVANS Car Stopping Apparatus Patent Print |
| 1931 JOSEPH Game Apparatus Patent Print Art |
| 1931 MAHONEY Amusement Apparatus Patent Print |
| 1931 HERRICK Initiating Apparatus Patent Print |
| 1931 GEBERT ALBERT Game Apparatus Patent Print |
| 1931 SPAFFORD LEWIS Game Apparatus Patent Print |
| 1931 CLAUSEN Exercising Apparatus Patent Print |
| 1931 ALEXANDER Game Apparatus Patent Print Art |
| 1931 MALLARD LOGAN Game Apparatus Patent Print |
| 1931 ARMAND NADEAU Game Apparatus Patent Print |
| 1931 LUSSE Amusement Car Apparatus Patent Print |
| 1931 MAURITZ Game-Scoring Apparatus Patent Print |
| 1931 GRAY Railway Switch Apparatus Patent Print |
| 1931 RENN GEORGE Game Apparatus Patent Print Art |
| 1931 DAVIS JR Siphon Apparatus Patent Print Art |
| 1931 MAY FINN Submergible Apparatus Patent Print |
| 1931 TRUST Pin Setting Apparatus Patent Print |
| 1931 LEVITT DAVID Game Apparatus Patent Print |
| 1931 HICKS RAYMOND Timing Apparatus Patent Print |
| 1931 WILLIAM TURRALL Game Apparatus Patent Print |
| 1931 SHOEMAKER Exercising Apparatus Patent Print |
| 1931 MCGEE Life Saving Apparatus Patent Print |
| 1931 GILSON Motor Control Apparatus Patent Print |
| 1931 HOPPES Playground Apparatus Patent Print |
| 1931 PETER CLAUSEN Game Apparatus Patent Print |
| 1931 ZIERDT Electrical Apparatus Patent Print |
| 1931 DOS SANTOS Amusement Apparatus Patent Print |
| 1931 LUZERN Amusement Apparatus Patent Print Art |
| 1931 HEINA Portable Radio Apparatus Patent Print |
| 1931 EARLEY MARTIN Game Apparatus Patent Print |