Columbia subject headings:
Art museums--Germany--Ruhr (Region)
Art--Germany--Ruhr (Region)
RuhrKunstMuseen.
Harvard subject headings:
Art museums--Germany--Ruhr (Region)
Art--Germany--Ruhr (Region).
RuhrKunstMuseen.
Princeton subject headings:
Art museums--Germany--Ruhr (Region).
Art--Germany--Ruhr (Region).
RuhrKunstMuseen.