Columbia subject headings:
Harvard subject headings:
Architecture, Industrial--Germany--Ruhr (Region)
Cities and towns--Germany--Ruhr (Region)
Lifestyles--Germany--Ruhr (Region)
Ruhr (Germany : Region)--Pictorial works.
Ruhr (Germany : Region)--Social life and customs.
Princeton subject headings:
Architecture, Industrial--Germany--Ruhr (Region).
Cities and towns--Germany--Ruhr (Region).
Lifestyles--Germany--Ruhr (Region).
Ruhr (Germany : Region)--Pictorial works.
Ruhr (Germany : Region)--Social life and customs.