Columbia subject headings:
Labor unions--Law and legislation--United States--Cases--Indexes.
Labor unions--Recognition--Law and legislation--United States--Cases--Indexes.
Harvard subject headings:
Labor unions--Law and legislation--United States--Cases--Indexes.
Labor unions--Recognition--Law and legislation--United States--Cases--Indexes.
Princeton subject headings:
Labor unions--Law and legislation--United States--Cases--Indexes.
Labor unions--Recognition--Law and legislation--United States--Cases--Indexes.