Sources: “A Concise History of Poland” (2019) by Jerzy Lukowski and W.H. Zawadzki.. Cambridge University Press, Cambridge, UK. https://www.britannica.com/place/Poland/Communist-Poland Audio: Inritter: https://commons.wikimedia.org/wiki/File:Rorate_Caeli_~_Gregorian_Chant.ogg Pictures requiring attribution: https://pastebin.com/bJPFC4mA #Poland #history