The National Union For Sport And Technology (Народен Съюз За Спорт И Техника) existed from 1947 when it was created from an amalgamation of other Unions and was itself merged out of existence in 1951 becoming part of the Union For Fighters Against Fascism And Capitalism. This makes these fairly easy to date, specially when coupled with a document with "195 " dates printed in them.
Another document this one with a twist. It belonged to a Bulgarian Jew, a rarity at this time as shortly after the end of the Second World War the Jewish population of Bulgaria all but vanished parallel to the creation of a Jewish state in Palestine.
It also has quite a lot of information and use for the short period it would have been valid.