Columbia subject headings:
Socialism--Austria--History--Congresses.
Socialism--Germany--History--Congresses.
Harvard subject headings:
Socialism--Austria--Congresses.
Socialism--Austria--History--Congresses.
Socialism--Germany--Congresses.
Socialism--Germany--History--Congresses.
Princeton subject headings:
Socialism--Austria--History--Congresses.
Socialism--Germany--History--Congresses.