Columbia subject headings:
Harvard subject headings:
Europe--History--Congresses.
Europe--Politics and government--Congresses.
Holy Roman Empire--History--Congresses.
Holy Roman Empire--Politics and government--Congresses.
Princeton subject headings:
Europe--History--Congresses.
Europe--Politics and government--Congresses.
Holy Roman Empire--History--Congresses.
Holy Roman Empire--Politics and government--Congresses.