Columbia subject headings:
Harvard subject headings:
Labor movement--Portugal--History--20th century--Congresses.
Portugal--Social conditions--20th century--Congresses.
Social conflict--Portugal--History--20th century--Congresses.
Strikes and lockouts--Portugal--History--20th century--Congresses.
Princeton subject headings:
Labor movement--Portugal--History--20th century--Congresses.
Portugal--Social conditions--20th century--Congresses.
Social conflict--Portugal--History--20th century--Congresses.
Strikes and lockouts--Portugal--History--20th century--Congresses.