Columbia subject headings:
Neutrality--United States.
United States--Foreign relations--20th century.
United States. Congress. Senate--History--20th century.
Harvard subject headings:
Neutrality--United States.
United States--Foreign relations--20th century.
United States. Congress. Senate--History--20th century.
Princeton subject headings:
Neutrality--United States--History--20th century.
United States--Foreign relations--20th century.
United States. Congress. Senate--History--20th century.