Columbia subject headings:
Working class--Europe--Congresses.
Working class--Europe--Folklore--Congresses.
Working class--Museums--Europe.
Harvard subject headings:
Working class--Europe--Congresses.
Working class--Europe--Folklore--Congresses.
Working class--Museums--Europe.
Princeton subject headings:
Working class--Europe--Folklore--Congresses.
Working class--Europe--History--Congresses.