| Number | Date | Country | Kind |
|---|---|---|---|
| 4002680 | Jan 1990 | DEX |
| Number | Name | Date | Kind |
|---|---|---|---|
| 4857001 | Nakano et al. | Aug 1989 | |
| 5000694 | Komatsu | Mar 1991 | |
| 5013255 | Juret et al. | May 1991 | |
| 5053199 | Keiser et al. | Oct 1991 |
| Entry |
|---|
| "Die Chipkarte am Schlusselbund", appearing in Design & Elektronik, Jan. 23, 1990, p. 12. |