Columbia subject headings:
Harvard subject headings:
Madrid (Spain)--Social conditions.
Social conflict--Spain--Madrid.
Spain--Politics and government--1931-1939.
Syndicalism--Spain--Madrid.
Princeton subject headings:
Labor unions--Spain--Madrid--History--20th century.
Social conflict--Spain--Madrid--History--20th century.
Strikes and lockouts--Spain--Madrid--History--20th century.
Working class--Spain--Madrid--History--20th century.