Columbia subject headings:
Harvard subject headings:
Europe--Politics and government--20th century--Congresses.
Germany--Politics and government--20th century--Congresses.
Liberalism--Europe--History--20th century--Congresses.
Liberalism--Germany--History--20th century--Congresses.
Princeton subject headings:
Europe--Politics and government--20th century--Congresses.
Germany--Politics and government--20th century--Congresses.
Liberalism--Europe--History--20th century--Congresses.
Liberalism--Germany--History--20th century--Congresses.