Columbia subject headings:
Harvard subject headings:
Dams--Germany--Ruhr (Region)--History--20th century.
Great Britain. Royal Air Force. Squadron, 617.--History.
Ruhr (Germany : Region)--History
World War, 1939-1945--Aerial operations, British.
World War, 1939-1945--Destruction and pillage--Germany--Ruhr (Region)
Princeton subject headings:
Dams--Germany (West)--Ruhr (Region)--History--20th century.
Great Britain. Royal Air Force. Squadron, 617--History.
Ruhr (Germany : Region)--History.
World War, 1939-1945--Aerial operations, British.
World War, 1939-1945--Destruction and pillage--Germany (West)--Ruhr (Region).