Columbia subject headings:
Mexico--Relations--Spain.
Spain--Relations--Mexico.
Spaniards--Mexico--History.
Harvard subject headings:
Exiles--Mexico--Congresses.
Exiles--Spain--Congresses.
Mexico--Emigration and immigration--History--Congresses.
Migration, Internal--Spain--Congresses.
Spain--Emigration and immigration--History--Congresses.
Spaniards--Mexico--History--Congresses.
Princeton subject headings:
Mexico--Relations--Spain.
Spain--Relations--Mexico.
Spaniards--Mexico--History.