Columbia subject headings:
Mexico--Foreign relations--1910-1946--Sources.
Mexico--Foreign relations--Spain--Sources.
Mexico--History--Revolution, 1910-1920--Participation, Spanish--Sources.
Spain--Foreign relations--Mexico--Sources.
Harvard subject headings:
Mexico--Foreign relations--1910-1946--Sources.
Mexico--Foreign relations--Spain--Sources.
Mexico--History--Revolution, 1910-1920--Participation, Spanish--Sources.
Spain--Foreign relations--Mexico--Sources.
Princeton subject headings:
Mexico--Foreign relations--1910-1946.
Mexico--Foreign relations--Spain.
Spain--Foreign relations--Mexico.