Columbia subject headings:
Neutrality.
World War, 1914-1918--Diplomatic history.
World War, 1914-1918--Economic aspects--United States.
World War, 1914-1918--Naval operations--Submarine.
World War, 1914-1918--United States.
Harvard subject headings:
Neutrality--United States.
Neutrality.
World War, 1914-1918--Diplomatic history
Princeton subject headings:
Neutrality--United States.
Neutrality.
World War, 1914-1918--Diplomatic history.