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
2 March 1974 - Institutional correspondence A letter from Karl Denim, S. S. Kush and Joshua Jericho in defence of Tony Shafrazi
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