Columbia subject headings:
Christian sociology--Germany--Ruhr (Region)
Ruhr (Germany : Region)--Religious life and customs.
Harvard subject headings:
Christian sociology--Germany--Ruhr (Region)
Christian sociology--Germany--Ruhr River Valley.
Ruhr (Germany : Region)--Religious life and customs.
Ruhr River Valley (Germany)--Religious life and customs.
Princeton subject headings:
Christian sociology--Germany--Ruhr (Region).
Ruhr (Germany : Region)--Religious life and customs.