Columbia subject headings:
Automobiles--Law and legislation--United States.
Bus lines--United States.
Carriers--United States.
Law reports, digests, etc.--United States.
Harvard subject headings:
Automobiles--Law and legislation--United States
Bus lines--United States.
Buses.
Carriers--United States.
Carriers.
Law reports, digests, etc.--United States.
Princeton subject headings:
Automobiles--Law and legislation--United States.
Buses.
Carriers.
Law reports, digests, etc.--United States.