On October 16, 1987, a sheetlet on the topic “30 years of Soviet space research” was issued in Bulgaria. This in both perforated as well as imperforated version. The sheetlet was printed in blue-violet color. With the inscription “1957 SPUTNIK 1” (СПУТНИК) at the top and “1964 WOSTOK 1” (BOCTOK) at the bottom, the sheetlet was faulty. Therefore the sheetlet was quickly withdrawn and reissued corrected on December 24, 1987, with the inscriptions “1957 SPUTNIK” and “1961 WOSTOK”, the corrected sheetlet was printed in violet-black color. The quanity of the withdrawn sheetlets were 1018 (perforated) and 550 (imperforated).