Columbia subject headings:
Harvard subject headings:
Portugal--History--1910-1974--Congresses.
Portugal--History--1974---Congresses.
Portugal--Intellectual life--20th century--Congresses.
Princeton subject headings:
Portugal--History--1910-1974--Congresses.
Portugal--History--1974---Congresses.
Portugal--Intellectual life--20th century--Congresses.