Columbia subject headings:
Canada--Labor unions--Mergers.
Labor unions--Canada--Consolidation.
Labor unions--Great Britain--Consolidation.
Labor unions--Mergers--Great Britain.
Labor unions--United States--Consolidation.
United States--Labor unions--Mergers.
Harvard subject headings:
Labor unions--Mergers--Canada.
Labor unions--Mergers--Great Britain.
Labor unions--Mergers--United States.
Princeton subject headings:
Labor unions--Mergers--Canada.
Labor unions--Mergers--Great Britain.
Labor unions--Mergers--United States.