| Number | Name | Date | Kind |
|---|---|---|---|
| D283818 | Skaggs | May 1986 | |
| D288930 | Barbera et al. | Mar 1987 | |
| D289306 | Burnstein et al. | Apr 1987 | |
| 4464652 | Lapson et al. | Aug 1984 | |
| 4635496 | McTyre | Jan 1987 | |
| 4754268 | Mori | Jun 1988 |
| Entry |
|---|
| Measurement Systems, Inc-Brochure, 10-18-84, p. 17, (Model 622-20 Digital Output Trackball--lower right corner). |