Columbia subject headings:
Harvard subject headings:
Communism--Italy--History
Kommunisticheskai︠a︡ partii︠a︡ Sovetskogo Soi︠u︡za. Sʺezd (20th : 1956 : Moscow, Russia)
Socialism--Italy--History
Princeton subject headings:
Socialism--Congresses.
Socialism--Italy--Congresses.