Columbia subject headings:
Harvard subject headings:
Europe--History--20th century.
Switzerland--Armed Forces--History.
Switzerland--Defenses--History.
Switzerland--History--20th century.
World War, 1939-1945--Aerial operations, British.
World War, 1939-1945--Aerial operations, Swiss.
World War, 1939-1945--Switzerland.
Princeton subject headings:
Europe--History--20th century.
Switzerland--Armed Forces--History.
Switzerland--Defenses--History.
Switzerland--History--20th century.
World War, 1939-1945--Aerial operations, British.
World War, 1939-1945--Aerial operations, Swiss.
World War, 1939-1945--Switzerland.