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
25 September and 11 October 1972 - Personal correspondence A letter from Catherine Freedberg to Roland Penrose, including the reply
Cambridge, Massachusetts, 14 May 1973 - Institutional correspondence Catherine Freedberg's letter to Patricia Failing