| Issuer | Date | Desc | State | ||
| - | no image | Gabon | 1/9/1991 | empty sheet (#21855) | incomplete |
| - | no image | Gabon | 2/26/1991 | empty sheet (#21856) | incomplete |
| - | no image | Gabon | 6/19/1991 | empty sheet (#21857) | incomplete |
| - | no image | Gabon | 9/18/1991 | empty sheet (#21858) | incomplete |