Columbia subject headings:
Harvard subject headings:
Liberty--Philosophy--Congresses.
Philosophy, German--18th century--Congresses.
Philosophy, German--19th century--Congresses.
Political science--Germany--History--Congresses.
Princeton subject headings:
Liberty--Philosophy--Congresses.
Philosophy, German--18th century--Congresses.
Philosophy, German--19th century--Congresses.
Political science--Germany--History--Congresses.