Columbia subject headings:
Communism--Italy--History--20th century--Congresses.
Grieco, Ruggero--Congresses.
Peasants--Political activity--Italy--History--20th century--Congresses.
Harvard subject headings:
Communism--Italy--History--20th century--Congresses.
Grieco, Ruggero--Congresses.
Peasants--Italy--Political activity--History--20th century--Congresses.
Princeton subject headings:
Communism--Italy--History.
Communists--Italy--Biography.
Grieco, Ruggero.
Partito comunista italiano--History.