Columbia subject headings:
Espionage--Switzerland--History--20th century.
World War, 1939-1945--Secret service--Switzerland.
Harvard subject headings:
Espionage--Switzerland.
Switzerland--History, Military--20th century.
World War, 1939-1945--Secret service--Switzerland.
Princeton subject headings:
Espionage--Switzerland--History--20th century.
World War, 1939-1945--Secret service--Switzerland.