Columbia subject headings:
Industrial relations--United States.
Labor laws and legislation--United States.
Labor unions--Law and legislation--United States.
Labor unions--United States.
Harvard subject headings:
Industrial relations--United States
Labor laws and legislation--United States
Labor unions--Law and legislation--United States
Labor unions--United States
Princeton subject headings:
Industrial relations--United States.
Labor laws and legislation--United States.
Labor unions--Law and legislation--United States.
Labor unions--United States.