Columbia subject headings:
Industrial relations--United States.
Labor economics.
Labor laws and legislation--United States.
Labor unions--United States.
Working class--United States.
Harvard subject headings:
Industrial relations--United States
Labor economics.
Labor laws and legislation--United States
Labor supply--United States.
Labor unions--United States
Working class--United States
Princeton subject headings:
Industrial relations--United States.
Labor economics.
Labor laws and legislation--United States.
Labor market--United States.
Labor unions--United States.