Sarah Greenough is the curator of photographs at the National Gallery of Art. She has written many books about photography, including Alfred Stieglitz: Photographs & Writings (NGA 1983), Harry Callahan (Bulfinch 1998), Walker Evans (NGA, 1991), Paul Stand: An American Vision (NGA, 1991), & On the Art of Fixing a Shadow (Bulfinch, 1989).