Columbia subject headings:
Harvard subject headings:
Sabotage--United States
World War, 1914-1918--Secret service--Germany
World War, 1914-1918--United States
World War, 1939-1945.
Princeton subject headings:
Sabotage--United States.
World War, 1914-1918--Secret service--Germany.
World War, 1914-1918--United States.
World War, 1939-1945.