Columbia subject headings:
Sabotage--United States--History--20th century.
World War, 1914-1918--Secret service--Germany.
Harvard subject headings:
Sabotage--United States--History--20th century.
World War, 1914-1918--Secret service--Germany
Princeton subject headings:
Sabotage--United States--History--20th century.
World War, 1914-1918--Secret service--Germany.