Columbia subject headings:
Harvard subject headings:
Railroads--Canada--Directories.
Railroads--Canada--Passenger traffic--Periodicals.
Railroads--Canada--Timetables.
Railroads--Mexico--Directories.
Railroads--Mexico--Passenger traffic--Periodicals.
Railroads--Mexico--Timetables.
Railroads--United States--Directories
Railroads--United States--Passenger traffic--Periodicals.
Railroads--United States--Timetables.
Princeton subject headings:
Railroads--Canada--Timetables.
Railroads--Mexico--Timetables.
Railroads--North America--Passenger traffic.
Railroads--United States--Timetables.