Columbia subject headings:
Communism--Italy--History--Sources.
Partito comunista d'Italia--History--Sources.
Harvard subject headings:
Communism--Italy--History--Sources.
Partito comunista d'Italia--History--Sources.
Princeton subject headings:
Communism--Italy--History--20th century--Sources.
Communist parties--Italy--History--20th century--Sources.
Partito comunista d'Italia--History--Sources.