Columbia subject headings:
Environmental policy--Mexico.
Environmental policy--United States.
Environmental protection--Mexican-American Border Region.
Mexico--Foreign relations--United States.
Mexico--Relaciones exteriores--Estados Unidos.
Política ambiental--Estados Unidos.
Política ambiental--Mexico.
Protección del medio ambiente--Frontera mexicanoamericana.
United States--Foreign relations--Mexico.
United States--Relaciones exteriores--Mexico.
Harvard subject headings:
Environmental policy--Mexico
Environmental policy--United States
Environmental protection--Mexican-American Border Region.
Mexico--Foreign relations--United States.
United States--Foreign relations--Mexico.
Princeton subject headings:
Environmental policy--Mexico.
Environmental policy--United States.
Environmental protection--Mexican-American Border Region.
Mexico--Foreign relations--United States.
United States--Foreign relations--Mexico.