Bulgaria issued a miniature sheet on Conference on Security and Co-operation in Europe on 29 Oct 1974. The miniature sheet had four stamps of 13 st denomination each and featured Doves, Map of Europe, Olive Branch & Inscription. The MS had a print run of 260,000.
On 02 Mar 1979, the same miniature sheet was issued with Overprints on EUROPA on each stamp and Beograd 1977, Helsinki 1975, Madrid 1980 on side margins. This overprinted MS had a print run of only 35,000. Each MS was numbered. It has a high catalogue value.