Columbia subject headings:
Harvard subject headings:
Democracy--Germany--Congresses.
Oertzen, Peter von--Political and social views--Congresses.
Political parties--Germany--Congresses.
Socialism and education--Germany--Congresses.
Socialism--Germany--Congresses.
Princeton subject headings:
Democracy--Germany--Congresses.
Oertzen, Peter von--Political and social views--Congresses.
Political parties--Germany--Congresses.
Socialism and education--Germany--Congresses.
Socialism--Germany--Congresses.