He has worked extensively for international organisations for over 20 years — including two fulltime periods as Counsel (Taxation) in the Legal Department of the International Monetary Fund, Washington DC, USA (1990 - 1991) and as Head,
Central and Eastern Europe and NIS Program, Fiscal Affairs
Division, Organisation for Economic Co-operation and Development,
Paris, France (1992 - 1995).
Bittle has participated in several group shows in the U.S. and abroad including The Queens Museum; The Arsenal,
Central Park; Radiator Arts, LIC; Root
Division, San Francisco; The Observatory Room, Brooklyn; Hewitt Gallery of Art, Marymount College; The Emerald Triangle Museum, SC; Akus Gallery, Connecticut; Proto Gallery, Hoboken; Wrong Gallery, Marfa; Emily Harvey Foundation, ESBA - TALM, Angers, France, and CNEAI,
Paris.
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).