Their collection included work by Joseph Beuys, Mel Bochner, Lee Bontecou, Christo, Joseph Cornell, Hanne Darboven, Jan Dibbets, Lucio Fontana, Eva Hesse, Donald Judd, On Kawara, Yves Klein, Joseph Kosuth, Sol LeWitt, Piero Manzoni, John McCracken, Mario Merz, Robert Morris, Bruce Nauman, Louise Nevelson, Claes Oldenburg, Giulio Paolini, Michelangelo Pistoletto, Fred Sandback, George Segal, Richard Serra, Richard Tuttle, Cy Twombly, Günther Uecker, Tom Wesselmann, and Douglas Wheeler.