Columbia subject headings:
Labor unions and communism--Poland--Wielkopolska--History.
Labor unions--Political activity--Poland--Wielkopolska--History.
Harvard subject headings:
Labor unions and communism--Poland--Wielkopolska--History.
Labor unions--Poland--Wielkopolska--Political activity--History.
Princeton subject headings:
Labor unions--Poland--Wielkopolska--Political activity.
Labor unions--Poland--Wielkopolska.