Columbia subject headings:
Europe--Foreign relations--Congresses.
Europe--Politics and government--Congresses.
Peace--Congresses.
Harvard subject headings:
Europe--Politics and government--18th century--Congresses.
Europe--Politics and government--19th century--Congresses.
Europe--Politics and government--20th century--Congresses.
Peace--History--Congresses.
Princeton subject headings:
Europe--Foreign relations--Congresses.
Europe--Politics and government--Congresses.
Peace--Congresses.