Columbia subject headings:
Art, European--20th century--Exhibitions.
Art, European--21st century--Exhibitions.
Art--Private collections--Germany--Waldenbuch--Exhibitions.
Hoppe-Ritter, Marli, 1948---Art collections--Exhibitions.
Museum Ritter (Waldenbuch, Germany)--Exhibitions.
Square in art--Exhibitions.
Harvard subject headings:
Art, European--20th century--Exhibitions
Art, European--21st century--Exhibitions
Art, Modern--20th century--Themes, motives--Exhibitions
Art, Modern--21st century--Themes, motives--Exhibitions
Art--Germany--Waldenbuch--Exhibitions.
Art--Private collections--Germany--Waldenbuch--Exhibitions.
Hoppe-Ritter, Marli, 1948---Art collections--Exhibitions.
Museum Ritter (Waldenbuch, Germany)--Exhibitions.
Museum Ritter--Exhibitions.
Square in art--Exhibitions.
Princeton subject headings:
Art, European--20th century--Exhibitions.
Art, European--21st century--Exhibitions.
Art--Private collections--Germany--Waldenbuch--Exhibitions.
Hoppe-Ritter, Marli, 1948---Art collections--Exhibitions.
Museum Ritter (Waldenbuch, Germany)--Exhibitions.
Square in art--Exhibitions.