Columbia subject headings:
Harvard subject headings:
Aeronautics, Military
Aeronautics, Military--Great Britain.
Aeronautics, Military--Spain.
Barcelona (Spain)--History.
Spain--History--Civil War, 1936-1939.
Princeton subject headings:
Aeronautics, Military--Great Britain.
Aeronautics, Military--Spain.
Aeronautics, Military.
Barcelona (Spain)--History.
Spain--History--Civil War, 1936-1939.