Stamps of Bulgaria, International Writers Conference issue
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postage
1977, Jun 7 International Writers Conference issue unwmk p. 13
| - | 23s | multi | congress emblem | — | — | |
| - | 23s | multi | — | — |
1 to 2 of 2
| - | 23s | multi | congress emblem | — | — | |
| - | 23s | multi | — | — |