Columbia subject headings:
Labor unions--Elections--Law and legislation--United States.
Labor unions--Officials and employees--Legal status, laws, etc.--United States.
Harvard subject headings:
Labor unions--Elections--Law and legislation--United States.
Labor unions--United States--Officials and employees--Legal status, laws, etc.
Princeton subject headings:
Labor unions--Elections--Law and legislation--United States.
Labor unions--United States--Officials and employees--Legal status, laws, etc.