| Number | Name | Date | Kind |
|---|---|---|---|
| 4189235 | Guter et al. | Feb 1980 | |
| 4210685 | Login et al. | Jul 1980 | |
| 4234621 | Fieux | Nov 1980 | |
| 4293776 | Sick et al. | Oct 1981 |
| Entry |
|---|
| "BEP Specification for Paper: Distinctive," Department of the Treasury, Bureau of Engraving and Printing, Washington, D.C. 20228, P: D-1f Jun. 24, 1981. |