Marcel Duchamp : a retrospective exhibition organized by the Philadelphia Museum of Art and the Museum of Modern Art, New York, made possible in part by a grant from the National Endowment for the Arts; Exhibition prepared; Philadelphia Museum of Art, Sept. 22 to Nov. 11, 1973, the Museum of Modern Art, New York, Dec. 3, 1973 to Febr. 10, 1974; the Art Institute of Chicago, March 9 to April 21, 1974