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
Farmington, Connecticut, 20 September 1946 - Personal correspondence James Thrall Soby's letter to William Lieberman