Columbia subject headings:
Carriers--United States.
Interstate commerce--United States.
Railroad law--United States.
Railroads--United States--Employees.
Transportation, Automotive--Law and legislation--United States.
Transportation--Law and legislation--United States.
Harvard subject headings:
Carriers--United States.
Railroad law--United States.
Railroads--United States--Employees
Transportation, Automotive--Law and legislation--United States.
Princeton subject headings:
Carriers--United States.
Railroad law--United States.
Railroads--United States--Employees.
Transportation, Automotive--Law and legislation--United States.