Columbia subject headings:
Spain--History--19th century--Congresses.
Spain--History--20th century--Congresses.
Harvard subject headings:
Spain--History--19th century--Congresses.
Spain--History--19th century--Historiography--Congresses.
Spain--History--20th century--Congresses.
Spain--History--20th century--Historiography--Congresses.
Princeton subject headings:
Spain--History--19th century--Congresses.
Spain--History--19th century--Historiography--Congresses.
Spain--History--20th century--Congresses.
Spain--History--20th century--Historiography--Congresses.