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| Cert Num | 1221743 |
| Cert Date | 2010-05-25 |
| Catalog Number | C21 |
| Country | USA |
| Year | 1937 |
| Denom | 20c |
| Color | Green |
| Grade | F-VF 75 |
| Description | Mint OGnh |
| Opinion | it is a genuine unused, o.g., never hinged, bottom margin Plate No. 21623 block of six with light creases in the selvage. |
| Cert Link | http://psestamp.com/Cert/1221743 |