| Number | Name | Date | Kind |
|---|---|---|---|
| 717966 | Bourk | Jan 1903 | |
| 3833765 | Hilborn et al. | Sep 1974 | |
| 3937939 | Frankel | Feb 1976 | |
| 4360892 | Endfield | Nov 1982 | |
| 4555193 | Stone | Nov 1985 | |
| 4668194 | Naryanan | May 1987 |
| Entry |
|---|
| Niederreiter, "Single Key Element Data Input", IBM Technical Disclosure Bulletin, vol. 19, No. 7, Dec. 76, pp. 2585-2586. |