Catalogue published in conjunction with an exhibition at the Stedelijk Museum, Amsterdam, April 17 - June 6, 1971. Part 2 out of 3. Includes a laid-in loose catalogue sheet (41.5 x 55 cm.) folded into fourths. Profusely illustrated in black-and-white. Includes a chronology and bibliography. With contributions by George Brecht, Robert Filiou, Karl Gerstener, Deiter Roth, Arman and others.