Columbia subject headings:
Strikes and lockouts--Spain--Vizcaya--History.
Working class--Spain--Vizcaya--History.
Harvard subject headings:
Strikes and lockouts--Spain--Vizcaya--History.
Working class--Spain--Vizcaya--History.
Princeton subject headings:
Industrial relations--Spain--Vizcaya--History--20th century.
Strikes and lockouts--Spain--Vizcaya--History--20th century.
Working class--Spain--Vizcaya--History--20th century.