Columbia subject headings:
Canada--Relations--Mexico--Periodicals.
Canada--Relations--United States--Periodicals.
Mexico--Relations--Canada--Periodicals.
Mexico--Relations--United States--Periodicals.
United States--Relations--Canada--Periodicals.
United States--Relations--Mexico--Periodicals.
Harvard subject headings:
Canada--Relations--Mexico--Periodicals.
Canada--Relations--United States--Periodicals.
Mexico--Relations--Canada--Periodicals.
Mexico--Relations--United States--Periodicals.
United States--Relations--Canada--Periodicals.
United States--Relations--Mexico--Periodicals.
Princeton subject headings:
Canada--Relations--Mexico--Periodicals.
Canada--Relations--United States--Periodicals.
Mexico--Relations--Canada--Periodicals.
Mexico--Relations--United States--Periodicals.
United States--Relations--Canada--Periodicals.
United States--Relations--Mexico--Periodicals.