Columbia subject headings:
Harvard subject headings:
Mexico--Foreign relations--United States.
Mexico--Politics and government--1910-1946.
Obregón, Álvaro, 1880-1928
United States--Foreign relations--1921-1923.
United States--Foreign relations--Mexico.
Princeton subject headings:
Mexico--Foreign relations--United States.
Mexico--Politics and government--1910-1946.
Obregón, Álvaro, 1880-1928.
United States--Foreign relations--1921-1923.
United States--Foreign relations--Mexico.