 Complete the following phrase:  Kazimierz Zakrzewski November 4, 1900 in Kraków  March 11, 1941 in Palmiry was a Polish historian and publicist, a professor of the University of Warsaw. Zakrzewski was a co-originator of the Polish syndicalist movement, activist of the trade union Związek Związków Zawodowych, and researcher of ancient history mainly late-ancient and the Byzantine culture. He wrote Historia Bizancjum History of the Byzantine Empire and co-authored the Polish popular history encyclopedia Wielka historia powszechna. During World War II, Zakrzewski was murdered by the Germans in a 