Roxbury, 22 November 1955 - Institutional correspondence Alexander Calder's letter to Willem Sandberg, dated 22 November 1955
Roxbury, 12 January 1956 - Institutional correspondence Alexander Calder's letter to Willem Sandberg, dated 12 January 1956
Jeanne Siegel (ed.), <em>Artwords: Discourse on the ‘60s and ‘70s</em>, Ann Arbor: UMI Research Press, 1985, 101-119 - Essay “How Effective Is Social Protest Art? (Vietnam)”