Columbia subject headings:
Harvard subject headings:
São Pedro da Cova (Portugal)--History--20th century.
Social conflict--Portugal--São Pedro da Cova--History--20th century.
Strikes and lockouts--Coal mining--Portugal--São Pedro da Cova--History--20th century.
Work environment--Portugal--São Pedro da Cova--History--20th century.
Princeton subject headings:
São Pedro da Cova (Portugal)--History--20th century.
Social conflict--Portugal--São Pedro da Cova--History--20th century.
Strikes and lockouts--Coal mining--Portugal--São Pedro da Cova--History--20th century.
Work environment--Portugal--São Pedro da Cova--History--20th century.