Including: «Bell / Irwin / Wheeler,» Tate Gallery, London, England (1970); «Fractured Light — Partial Scrim — Eye Level,»
Museum of Modern Art, New York (1970 - 1971); «Black Line Room Division + Extended Forms,» Whitney
Museum of American Art, New York (1977/2013); «48 Shadow Planes,»
Old Post Office, Washington DC (1983); «Two Running Violet V Forms,» Stuart Collection, UCSD, California (1983); «Ascending,» Musee d' Art Moderne deVille Paris, France (1994); «Double Diamond,» Musée d'Art Contemporain, Lyon, France (1997 - 1998); «1º 2º 3º 4º,»
Museum of Contemporary Art San Diego (1997); «The Central Garden,» J Paul Getty, Los Angeles (1998); «Architecture and Grounds,» DIA Art Foundation, Beacon, New York (2003); «Primaries and Secondaries,»
Museum of Contemporary Art San Diego (2007 - 2008); «Black on White,» J. Paul Getty
Museum, Los Angeles (2011 - 2012); «Niagara,» Albright - Knox Art Gallery, Buffalo, NY (2012); «Hedge Wedge,» San Diego Federal
Courthouse Building, San Diego (2012); «Double Blind,» Vienna Secession, Vienna (2013); «Miracle Mile,» Los Angeles County
Museum of Art, Los Angeles (2013); «Primordial Palm Garden,» Los Angeles County
Museum of Art (2010 - 2013).