Columbia subject headings:
Harvard subject headings:
Europe--History--1871-1918--Congresses.
Europe--History--1918-1945--Congresses.
Germany--History--1871-1918--Congresses.
Germany--History--1918-1933--Congresses.
Germany--History--Revolution, 1918--Congresses.
Germany--Politics and government--1871-1933--Congresses.
Princeton subject headings:
Germany--History--1871-1918.
Germany--History--1918-1933.
Germany--History--Revolution, 1918.
Germany--Politics and government--1871-1933.