Cambridge, Massachusetts, 20 November 1939 - Personal correspondence Josep Lluís Sert's letter to Pablo Picasso, dated 20 November 1939
Cambridge, Massachusetts, 8 December 1955 - Institutional correspondence Josep Lluís Sert's letter to Willem Sandberg
Cambridge, Massachusetts, 29 November 1980 - Institutional correspondence Josep Lluís Sert's letter to Dominique Bozo
Madrid, 31 July, and Cambridge, Massachusetts, 31 August 1981 - Institutional correspondence Álvaro Martínez Novillo's letter to Josep Lluís Sert, with reply
Cambridge (Massachusetts), 23 December 1976 - Institutional correspondence A letter from Josep Lluís Sert to Herschel B. Chipp
ca. 9 January 1939 - Personal correspondence Josep Lluís Sert's letter to Pablo Picasso, dated ca. 9 January 1939
Horseheads, New York, 23 January 1956 - Management of reproduction rights Hugh Thomas's letter to Alfred H. Barr Jr.
New York, 22 November 1969 - Institutional correspondence A letter from William S. Lieberman to Roland Dumas
New York, 7 March 1956 - Institutional correspondence William S. Lieberman's letter to Porter McCrary
New York, 20 September 1956 - Institutional correspondence William S. Lieberman's letter to Alfred H. Barr Jr.
New York, 7 June 1977 - Institutional correspondence William S. Lieberman's letter to Richard Oldenburg, dated 7 June 1977
New York, 1 June 1977 - Institutional correspondence William S. Lieberman's letter to Richard Oldenburg, dated 1 June 1977
New York, 31 May 1977 - Institutional correspondence William S. Lieberman's letter to Richard Oldenburg, dated 31 May 1977
New York, 5 July 1956 - Institutional correspondence William S. Lieberman's letter to Richard Griffith