London, 18 April 1980 - Institutional correspondence Nicholas Serota's letter to Roland Penrose, dated 18 April 1980
London, 1 May 1980 - Institutional correspondence Nicholas Serota's letter to Roland Penrose, dated 1 May 1980
New York, 10 September 1981 - Internal museum documents An internal letter from Louis Estrada to Eloise Ricciardelli