Essays in context : Unfolding the Netherlandish Diptych (exhibition 'Prayers and Portraits' : Washington, National Gallery of Art, 12 November 2006 - 4 February 2007 ; Antwerpen, Koninklijk Museum voor Schone Kunsten, 3 March - 27 May 2007) / - Hand, John Oliver (Harvard University Art Museums, 2006)