Columbia subject headings:
Harvard subject headings:
Archival materials--Conservation and restoration--Germany--Cologne--Congresses.
Archival materials--Digitization--Germany--Cologne--Congresses.
Cultural property--Protection--Germany--Cologne--Congresses.
Historisches Archiv der Stadt Köln--History--Congresses.
Princeton subject headings:
Archival materials--Conservation and restoration--Germany--Cologne--Congresses.
Archival materials--Digitization--Germany--Cologne--Congresses.
Cultural property--Protection--Germany--Cologne--Congresses.
Historisches Archiv der Stadt Köln--History--Congresses.