| Number | Name | Date | Kind |
|---|---|---|---|
| 3367099 | Kubovy et al. | Feb 1968 | |
| 3651632 | Shepherd | Mar 1972 | |
| 4069655 | Stahlecker et al. | Jan 1978 | |
| 4112659 | Stahlecker et al. | Sep 1978 | |
| 4245460 | Staufert et al. | Jan 1981 | |
| 4653266 | Oexler et al. | Mar 1987 | |
| 4769984 | Raasch et al. | Sep 1988 | |
| 5109663 | Stahlecker et al. | May 1992 | |
| 5111651 | Pohn et al. | May 1992 | |
| 5117622 | Stahlecker | Jun 1992 | |
| 5595058 | Billner | Jan 1997 | |
| 5685137 | Raasch | Nov 1997 |
| Number | Date | Country |
|---|---|---|
| 2532637 | Feb 1977 | DEX |
| Entry |
|---|
| German Patent Office Search Report, Feb. 3, 1997. |