Topic: PRL (the People's Republic of Poland)

The following Polish postage issues commemorate PRL anniversaries:

Fischer 622-623 - The new constitution of 1952
Fischer 747-756 - 10th PRL anniversary in 1954
Fischer 964-966 - 15th PRL anniversary in 1959
Fischer 1325-1326 - 20th PRL anniversary in 1964
Fischer 1355-1364 - 20th PRL anniversary in 1964
Fischer 1431-1432 - PRL-ZSRR anniversary in 1965
Fischer 1784-1792 - 25th PRL anniversary in 1969
Fischer 2178-2180 - 30th PRL anniversary in 1974
Fischer 2348 - PRL-ZSRR anniversary in 1977
Fischer 2492-2493 - 35th PRL anniversary in 1979
Sheet 63 - 35th PRL anniversary in 1979
Fischer 2533 - PRL-ZSRR anniversary in 1980
Fischer 3058-3061 - 45th PRL anniversary in 1989