The Head Office of State Archives — the PRADZIAD database of all vital records and civil registers kept in all archives (as of 2012) in Poland.
JewishGen — Jewish genealogy website.
Jewish Records Indexing Poland (JRI-Poland) - With 5 million records from more than 500 Polish towns -- from the Polish State Archives and other sources --
this is the largest fully-searchable database of indexes to Jewish vital records accessible online.
United States Holocaust Memorial Museum (USHMM) — United States Holocaust Memorial Museum w Waszyngtonie, DC.
Yad Vashem — Holocaust Research Institute
WIG Maps — The Archive of Maps of the Military Institute of Geography (1919 – 1939)
Virtual Shtetl — The Virtual Shtetl, Museum of the History of Polish Jews — the portal contains history briefs of the local Jewish communities across Poland.
The „Grodzka Gate – NN Theatre” Centre — The Center functions in Lublin for the preservation of the local cultural heritage and education. The website of the Centre contains among others 3D Models of the prewar Lublin, as well as the Lexicon of Lublin with descriptions of more than 600 buildings in Lublin before the war.