Christopher Williams, Untitled (Study in Gray), 1967 Citroen DS, Serial number: DS851360a, Color code: AC 118, Color name: gris etna, Color year: 1966, Studio Rhein Verlag, Düsseldorf, November 11, 2013, 2014, Image courtesy Galerie Gisela Capitain, Cologne; and David Zwirner, New York/London