Columbia subject headings:
Harvard subject headings:
P.S.O.E. (Political party)--History.
Socialism--Spain--20th century.
Socialism--Spain--History--20th century
Spain--Politics and government--20th century.
Princeton subject headings:
P.S.O.E. (Political party)--History.
Socialism--Spain--History--20th century.
Spain--Politics and government--20th century.