| Number | Name | Date | Kind |
|---|---|---|---|
| 1074430 | Hill | Sep 1913 | |
| 1108687 | Boorman | Aug 1914 | |
| 4635893 | Nelson | Jan 1987 | |
| 4717112 | Pirkle | Jan 1988 | |
| 4805859 | Hudson | Feb 1989 | |
| 4863140 | Schriner | Sep 1989 | |
| 4901972 | Judd et al. | Feb 1990 |
| Number | Date | Country |
|---|---|---|
| 8403573 | Sep 1984 | WOX |
| Entry |
|---|
| Global Computer Supplies Catalog, Mar. 1990, pp. 73-75. |
| Great Lakes Elec. Dist., Inc. flyer, Mar. 1, 1990. |