| 2694463 | Acoustic system for loud-speakers | |||
| 2622692 | Apparatus for imposing vibrato on sound | |||
| 2193399 | Acoustical apparatus | |||
| 2167625 | Speaker unit | |||
| 2080275 | Sound reproducing apparatus | |||
| 2014621 | Sound reproducer | |||
| 1926820 | Sound reproducing device | |||
| 1902609 | Loud speaker mounting |
| GB496504A | ||||
| FR908709A |