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
Philadelphia, 18 September 1957 - Institutional correspondence Henry Clifford's letter to Pablo Picasso
Madrid, 7 and 19 January 1981 - Institutional correspondence A letter from Enrique Calduch to Javier Tusell
Philadelphia, 1958 - Exhibition catalogue Catalogue for the exhibition Picasso: 75th Anniversary at the Philadelphia Museum of Art