Vormen van de kleur / New Shapes of Color, Stedelijk Museum, Amsterdam, The Netherlands, November 20, 1966 – January 15, 1967; Würtembergischer Kunstverein, Stuttgart, Germany, February 17 – March 27, 1967; Kunsthalle Bern, Bern, Switzerland, April 12 – May 15, 1967

April 12, 1967