Columbia subject headings:
Harvard subject headings:
Cologne (Germany)--History.
Cologne (Germany)--Relations--Germany--Prussia.
Cologne (Germany)--Social life and customs.
Prussia (Germany)--History--1815-1870.
Prussia (Germany)--History--1870-
Prussia (Germany)--Relations--Germany--Cologne.
Princeton subject headings:
Cologne (Germany)--History.
Cologne (Germany)--Relations--Prussia (Germany).
Cologne (Germany)--Social life and customs.
Prussia (Germany)--History--1815-1870.
Prussia (Germany)--History--1870-
Prussia (Germany)--Relations--Cologne (Germany)