Columbia subject headings:
Feudalism--Portugal--History--Congresses.
Feudalism--Spain--History--Congresses.
Land use--Portugal--History--Congresses.
Land use--Spain--History--Congresses.
Harvard subject headings:
Feudalism--Portugal--History--Congresses.
Feudalism--Spain--History--Congresses.
Land tenure--Portugal--History--Congresses.
Land tenure--Spain--History--Congresses.
Princeton subject headings:
Feudalism--Portugal--History--Congresses.
Feudalism--Spain--History--Congresses.
Land use--Portugal--History--Congresses.
Land use--Spain--History--Congresses.