Columbia subject headings:
Harvard subject headings:
Fundación Pablo Iglesias--Archives--Catalogs.
Labor unions--Spain--Officials and employees--Catalogs.
P.S.O.E. (Political party)--Archives--Catalogs.
Socialism--Spain--20th century--Sources--Bibliography--Catalogs.
Socialism--Spain--History--20th century--Sources--Bibliography--Catalogs.
Unión General de Trabajadores de España--Archives--Catalogs.
Princeton subject headings:
Labor unions--Spain--Archival resources.
Labor unions--Spain--History--Sources.
Labor unions--Spain--Officials and employees--Biography.
Labor unions--Spain--Officials and employees--Correspondence--Catalogs.
P.S.O.E. (Political party)--History--Sources.
Politicians--Spain--Biography.
Politicians--Spain--Correspondence--Catalogs.
Unión General de Trabajadores de España--History--Sources.