Columbia subject headings:
Holy Roman Empire--Congresses.
Political science--Italy--History--Congresses.
Political science--Spain--History--Congresses.
Harvard subject headings:
Holy Roman Empire--Congresses.
Political science--Italy--History--Congresses.
Political science--Spain--History--Congresses.
Princeton subject headings:
Holy Roman Empire--Congresses.
Political science--Italy--History--Congresses.
Political science--Spain--History--Congresses.