After the invasion of Poland by Nazi Germany and the Soviet Union in 1939 , Kostanecki was arrested on 6 November 1939 in his Alma mater during the German '' Sonderaktion Krakau '' against the Polish academics . He died in the Sachsenhausen concentration camp on 11 January 1940 .
Sonderaktion Krakau
Sonderaktion Krakau
Kazimierz Kostanecki