Columbia subject headings:
Chamizal.
Mexico--Boundaries.
Mexico--Foreign relations.
United States--Boundaries.
United States--Foreign relations.
Harvard subject headings:
El Chamizal (Mexico and Tex.)
Mexico--Boundaries--United States.
United States--Boundaries--Mexico.
Princeton subject headings:
El Chamizal (Mexico and Tex.)
Mexico--Boundaries--United States.
United States--Boundaries--Mexico.