Columbia subject headings:
Collective bargaining--United States--History.
Labor laws and legislation--United States--History.
Labor unions--Law and legislation--United States--History.
Labor unions--United States--History.
Harvard subject headings:
Collective bargaining--United States--History.
Labor laws and legislation--United States--History
Labor unions--Law and legislation--United States--History.
Labor unions--United States--History
Princeton subject headings:
Collective bargaining--United States--History.
Labor laws and legislation--United States--History.
Labor unions--Law and legislation--United States--History.
Labor unions--United States--History.