Columbia subject headings:
Industries--Germany--Düsseldorf--History.
Poor--Germany--Düsseldorf--History.
Unemployed--Germany--Düsseldorf--History.
Working class--Germany--Düsseldorf--History.
Harvard subject headings:
Industries--Germany--Düsseldorf--History.
Poor--Germany--Düsseldorf--History.
Unemployed--Germany--Düsseldorf--History.
Working class--Germany--Düsseldorf--History.
Princeton subject headings:
Industrialization--Germany--Düsseldorf--History.
Poor--Germany--Düsseldorf--History.
Unemployed--Germany--Düsseldorf--History.
Working class--Germany--Düsseldorf--History.