| 1931 THORP JOEL Horn FULTON CO Patent Print Art |
| 1931 DORSEY FARNUM Magnetic Horn Patent Print |
| 1931 TEMPLE FRED Amplifying Horn Patent Print |
| 1931 CONN LTD C G Horn Patent Print Art |
| 1931 STONEBACK SAMUEL Horn Patent Print Art |
| 1931 AUFIERO JOHN Motor Horn Patent Print Art |
| 1931 DE ANDIA Sound Amplifying Horn Patent Print |
| 1931 HORN Clutch Control Mechanism Patent Print |
| 1931 E A LAB INC Horn Patent Print Art |
| 1931 TEMPLE INC Amplifying Horn Patent Print Art |
| 1931 STOVER Horn Automatic Pitch Control Patent 17296 |
| 1931 LEUKHARDT Vacuum Operated Horn Patent Print |
| 1931 BROCKWAY Horn For Radio Speakers Patent |
| 1931 SVERRE RASMUSSEN Horn Or Amplifier Patent |
| 1931 BARNUM HAWLEY Sound Horn Patent Print Art |
| 1931 MILNOR JOSEPH Loud Speaker Horn Patent |
| 1931 KELLEY CECIL Signal Horn Patent Print Art |
| 1931 TRICO PRODUCTS CORP Horn Patent Print Art |
| 1931 AUFIERO JOHN Horn E A LAB INC Patent Print |
| 1931 MARINDIN HENRI Signal Horn Patent Print Art |
| 1931 WIEGAND Horn For Loud Speakers Patent Print |
| 1931 FULTON CO Horn Patent Print Art |
| 1931 GULICK EDWARD Horn CONN LTD C G Patent |
| 1931 ELY HIRAM Acoustic Horn Patent Print Art |