Columbia subject headings:
Harvard subject headings:
Communism--Europe--History--20th century--Congresses.
Dictatorship--Europe--History--20th century--Congresses.
Totalitarianism--History--20th century--Congresses.
Princeton subject headings:
Communism--Europe--History--20th century--Congresses.
Dictatorship--Europe--History--20th century--Congresses.
Totalitarianism--History--20th century--Congresses.