Columbia subject headings:
Harvard subject headings:
Communism--Italy--Emilia-Romagna--History--19th century.
Emilia-Romagna (Italy)--Politics and government.
Labor and laboring classes--Political activity--Italy--Emilia-Romagna--History--19th century.
Partito socialista rivoluzionario di Romagna--History.
Socialism--Italy--Emilia-Romagna--History--19th century.
Working class--Italy--Emilia-Romagna--Political activity--History--19th century.
Princeton subject headings:
Socialism--Italy--Romagna.