Columbia subject headings:
Aragon (Spain)--Foreign relations--Spain--Castile.
Castile (Spain)--Foreign relations--Spain--Aragon.
Castile (Spain)--History--Alfonso X, 1252-1284.
Harvard subject headings:
Aragon (Spain)--Foreign relations--Spain--Castile.
Castile (Spain)--Foreign relations--Spain--Aragon.
Castile (Spain)--History--Alfonso X, 1252-1284.
Princeton subject headings:
Alfonso X, King of Castile and Leon, 1221-1284.
Aragon (Spain)--Relations--Castile.
Castile (Spain)--History--Alfonso X, 1252-1284.
Castile (Spain)--Relations--Aragon.