Columbia subject headings:
Art, Russian--20th century--Private collections.
Art--Private collections--Germany--Aachen.
Ludwig, Irene--Art collections.
Ludwig, Peter, 1925-1996--Art collections.
Harvard subject headings:
Art, Modern--20th century--Catalogs
Art, Russian--20th century--Catalogs.
Art, Soviet--Catalogs.
Art--Private collections--Germany--Catalogs.
Ludwig, Irene--Art collections--Catalogs.
Ludwig, Peter, 1925-1996--Art collections--Catalogs.
Peter und Irene Ludwig Stiftung--Catalogs.
Princeton subject headings:
Art, Modern--20th century--Russia (Federation)--Catalogs.
Art, Modern--20th century--Soviet Union--Catalogs.
Art, Russian--20th century--Catalogs.
Art, Soviet--Catalogs.
Art--Private collections--Germany--Catalogs.
Catalogs.
Ludwig, Irene--Art collections--Catalogs.
Ludwig, Peter, 1925-1996--Art collections--Catalogs.