| Name | Issues/Designs | |||
| Balkan Studies Congress 1968 | 1966 | — | - ... | |
| 34th BSNC Congress | 1981 | — | - ... | |
| Conference for Peaceful Co-Existence in Europe | 1984 | — | - ... | |
| Conference for Security and Cooperation in Europe | 1981 | — | (2) - ..., ... b | |
| 8th Congress of Trade Unions in Bulgaria | 1977 | — | - ... | |
| 7th Congress of Trade Unions of Bulgaria | 1972 | — | - ... | |
| 17th International Geodesists Congress | 1983 | — | - ... | |
| Universal Postal Union Congress 1984 | 1984 | — | - ... |