Columbia subject headings:
Aeronautics and state--United States.
Aeronautics, Commercial--United States.
Aircraft industry--United States.
Local service airlines--United States.
Harvard subject headings:
Aeronautics, Commercial--United States
Airlines--United States
Princeton subject headings:
Aeronautics and state--United States.
Aeronautics, Commercial--United States.
Aircraft industry--United States.
Local service airlines--United States.