Columbia subject headings:
Historic buildings--Germany--Mülheim an der Ruhr.
Mülheim an der Ruhr (Germany)--Buildings, structures, etc.
Harvard subject headings:
Historic buildings--Germany--Mülheim an der Ruhr.
Mülheim an der Ruhr (Germany)--Buildings, structures, etc.
Princeton subject headings:
Historic buildings--Germany--Mülheim an der Ruhr.
Mülheim an der Ruhr (Germany)--Buildings, structures, etc.