Columbia subject headings:
Cologne (Germany)--Guidebooks.
Cologne (Germany)--History.
Historical markers--Germany--Cologne.
Monuments--Germany--Cologne.
Harvard subject headings:
Cologne (Germany)--Guidebooks.
Cologne (Germany)--History.
Historical markers--Germany--Cologne.
Monuments--Germany--Cologne.
Princeton subject headings:
Cologne (Germany)--Guidebooks.
Cologne (Germany)--History.
Historical markers--Germany (West)--Cologne.
Monuments--Germany (West)--Cologne.