Columbia subject headings:
Aeronautics, Commercial--United States--Finance.
Aeronautics, Commercial--United States--Passenger traffic.
Federal aid to transportation--United States.
Local service airlines--United States--Finance.
Harvard subject headings:
Aeronautics, Commercial--United States--Finance.
Aeronautics, Commercial--United States--Passenger traffic
Federal aid to transportation--United States.
Local service airlines--United States--Finance.
Princeton subject headings:
Aeronautics, Commercial--United States--Finance.
Aeronautics, Commercial--United States--Passenger traffic.
Federal aid to transportation--United States.
Local service airlines--United States--Finance.