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
Paris, 29 September 1945 - Institutional correspondence A letter from the secretary of the Association des Intellectuels italiens in France to Pablo Picasso