Columbia subject headings:
Germany--Foreign relations--Mexico.
Mexico--Foreign relations--Germany.
World War, 1914-1918--Diplomatic history.
World War, 1914-1918--United States.
Harvard subject headings:
Germany--Foreign relations--Mexico.
Germany--History--1871-1918.
Mexico--Foreign relations--Germany.
World War, 1914-1918--Causes
Zimmermann, Artur, 1864-1940.
Princeton subject headings: