Columbia subject headings:
Labor movement--Italy--History--20th century.
Labor unions--Italy--History--20th century.
Unione sindacale italiana--History.
Harvard subject headings:
Labor unions--Italy--Congresses
Syndicalism--Italy--Congresses.
Syndicalism--Italy--History--20th century--Sources.
Unione sindacale italiana--Congresses.
Princeton subject headings:
Labor unions--Italy--Congresses.
Syndicalism--Italy--Congresses.
Syndicalism--Italy--History--20th century--Sources.
Unione sindacale italiana--Congresses.