Columbia subject headings:
Harvard subject headings:
Germany (East)--Foreign relations--Greece--Congresses.
Greece--Foreign relations--Germany (East)--Congresses.
Socialism--History--20th century--Congresses.
Princeton subject headings:
Germany (East)--Foreign relations--Greece--Congresses.
Greece--Foreign relations--Germany (East)--Congresses.
Socialism--History--20th century--Congresses.