Columbia subject headings:
Aeronautics and state--United States.
Airlines--United States.
United States Civil Aeronautics Board.
United States. Civil Aeronautics Board.
Harvard subject headings:
Aeronautics and state--United States.
Airlines--United States
United States. Civil Aeronautics Board.
Princeton subject headings:
Aeronautics and state--United States.
Airlines--United States.
United States. Civil Aeronautics Board