Columbia subject headings:
Bus lines--Periodicals.
Buses--Periodicals.
Transportation, Automotive--Periodicals.
Transportation, Automotive--United States--Statistics.
Harvard subject headings:
Bus lines ;--Periodicals.
Buses--Periodicals.
Transportation, Automotive ;--Periodicals.
Transportation, Automotive--United States--Statistics.
Princeton subject headings:
Bus lines--United States--Statistics--Periodicals.
Buses--United States--Statistics--Periodicals.
Periodicals.
Transportation, Automotive--Periodicals.
Transportation, Automotive--United States--Periodicals.