Columbia subject headings:
650 0 Democracy--Spain--País Vasco--History--20th century.
Democracy--Spain--País Vasco--History--29th century.
Partido Socialista de Euskadi--History--20th century.
Harvard subject headings:
Democracy--Spain--País Vasco--History--20th century.
Democracy--Spain--País Vasco--History--21st century.
Partido Socialista de Euskadi--History--20th century.
Partido Socialista de Euskadi--History--21st century.
Princeton subject headings:
650 0 Democracy--Spain--País Vasco--Hitory--20th century.
Democracy--Spain--País Vasco--History--29th century.
Partido Socialista de Euskadi--History--20th century.