Columbia subject headings:
Harvard subject headings:
Gnocchi-Viani, Osvaldo, 1837-1917.
Socialism--History
Socialism--Italy
Socialism--Italy--History
Working class--Italy--Political activity--History.
Working class--Political activity--History.
Working class--Political activity--Italy--History.
Princeton subject headings:
Gnocchi-Viani, Osvaldo, 1837-1917.
Socialism--Italy--History.
Socialists--Italy--Biography.