Columbia subject headings:
Socialism--Europe--History--20th century.
Socialist parties--Europe--History--20th century.
Harvard subject headings:
Communism--Europe--History
Europe--History--1945-
Socialism--Europe--20th century.
Socialism--Europe--History--20th century
Socialist parties--Europe--History--20th century.
Princeton subject headings:
Socialism--Europe--History--20th century.
Socialist parties--Europe--History--20th century.