Columbia subject headings:
Harvard subject headings:
Correctional institutions--Germany--Cologne.
Germany. Geheime Staatspolizei
Graffiti--Germany--Cologne.
Inscriptions--Germany--Cologne.
World War, 1939-1945--Prisoners and prisons, German.
Princeton subject headings:
Germany. Geheime Staatspolizei
Graffiti--Germany.
Inscriptions--Germany.
Prisons--Germany--Cologne--History.
World War, 1939-1945--Prisoners and prisons, German.