Columbia subject headings:
Harvard subject headings:
Europe--Politics and government
Socialism--Europe--History
Socialism--Spain--History
Spain--Politics and government
Princeton subject headings:
Europe--Politics and government--19th century.
Europe--Politics and government--20th century.
Proletariat.
Socialism--Europe--History--19th century.
Socialism--Europe--History--20th century.
Socialism--Spain--History--19th century.
Socialism--Spain--History--20th century.
Spain--Politics and government--19th century.
Spain--Politics and government--20th century.