
Quote (1951), in 'What Abstract Art Means to Me' http://www.jstor.org/stable/4058250, George L. K. Morris, Willem De Kooning, Alexander Calder, Fritz Glarner, Robert Motherwell, Stuart Davis; as cited in the The Bulletin of the Museum of Modern Art, Vol. 18, No. 3, (Spring, 1951), pp. 2-15
1950s - 1960s