Columbia subject headings:
Art, German--Germany--North Rhine-Westphalia--20th century--Exhibitions.
Art, German--Germany--North Rhine-Westphalia--21st century--Exhibitions.
Harvard subject headings:
Art, German--Germany--North Rhine-Westphalia--20th century--Exhibitions.
Art, German--Germany--North Rhine-Westphalia--21st century--Exhibitions.
Princeton subject headings:
Art, German--Germany--North Rhine-Westphalia--20th century--Exhibitions.
Art, German--Germany--North Rhine-Westphalia--21st century--Exhibitions.