Topic: Trade Union congresses

The following Polish postage issues commemorate Trade Union congresses:

Fischer 386 - 7th Trade Union congress in Warsaw in 1945
Fischer 492-494 - Trade Union congress in 1949
Fischer 709-710 - 3rd Trade Union congress in Warsaw 1954
Fischer 808-809 - Trade Union for teachers 1955
Fischer 884 - Trade Union congress in Leipzig, Germany 1957
Fischer 1123 - 5th Trade Union congress in Moscow 1961
Fischer 1215 - 5th Trade Union congress in Warsaw 1962
Fischer 1622 - 6th Trade Union congress in 1967
Fischer 2056 - 12th/13th Trade Union congress in 1972
Fischer 2325 - 13th/14th Trade Union congress in 1976