Columbia subject headings:
Gussstahlfabrik Fried. Krupp (Essen, Germany)
Housing--Essen a.d. Ruhr.
Working class--Dwellings.
Harvard subject headings:
Dwellings--Germany--Ruhr.
Housing--Essen a.d. Ruhr.
Housing--Germany--Ruhr.
Krupp'sche Gussstahlfabrik.
Working class--Germany
Princeton subject headings:
Architecture, Domestic--Germany--Ruhr Valley Region.
Krupp family.
Ruhr Valley Region (Germany)--Buildings, structures, etc.
Working class--Dwellings--Germany--Ruhr Valley Region.