Poland: Polity Style: 1944-1989

22 Jul 1944	the Polish Committee of National Liberation (Polski Komitet Wyzwolenia Narodowego) proclaimed the assumption of state authority over the liberated territories of Poland in accordance with a manifesto dated 22 Jul 1944, Chełm (Rzeczpospolita, No. 1, 23 Jul 1944, pp. 1-2) [1]
22 Jul 1944 - 22 Jul 1952	Rzeczpospolita Polska \| Republic of Poland
22 Jul 1952	the Constitution of the People's Republic of Poland (Konstytucja Polskiej Rzeczypospolitej Ludowej) is adopted by the Legislative Sejm (Sejm Ustawodawczy) on 22 Jul 1952 and came into operation on the day (22 Jul 1952) specified by a Constitutional Law passed by the Legislative Sejm on 22 Jul 1952 (Poland Law Journal, No. 33, 23 Jul 1952, pp. 343-372)
22 Jul 1952 - 31 Dec 1989	Polska Rzeczpospolita Ludowa \| People's Republic of Poland
31 Dec 1989	the name of the state is changed in accordance with the amendments to the Constitution of the People's Republic of Poland passed by the Sejm on 29 Dec 1989 and by the Senate (Senat) on 30 Dec 1989, effective upon promulgation on 31 Dec 1989 (Poland Law Journal, No. 75, 31 Dec 1989, pp. 1147-1148) [2]

The Polish Committee of National Liberation (PCNL) was ostensibly appointed by the State National Council (Krajowa Rada Narodowa) and held a few meetings in Moscow before moving to the liberated territory. After the proclamation of the manifesto, the PCNL was installed in Lublin on 2 Aug 1944.
Full title: Ustawa z dnia 29 grudnia 1989 r. o zmianie Konstytucji Polskiej Rzeczypospolitej Ludowej.