Columbia subject headings:
Betti, Francesco, 1870-1920--Congresses.
Socialism--Italy--Massa-Carrara (Province)--History--Congresses.
Harvard subject headings:
Betti, Francesco, 1870-1920--Congresses.
Socialism--Italy--Massa-Carrara (Province)--Congresses.
Socialism--Italy--Massa-Carrara (Province)--History--Congresses.
Princeton subject headings:
Betti, Francesco, 1870-1920.