A book I have enjoyed rereading many times is " The New Vision" by Maria Morris Hambourg from the Metropolitan Museum of Art. While it seems to follow the usual "everything follows Stieglitz" trend, a careful reading allows a line through Clarence Whites' Students to the Modernism of the 1920's and 30's. Christoper Phillips essay is good and makes me want to get a copy of his "Photography in the Modern Era: European Documents and Critical Writings, 1913-1940 "