Madrid, 3 September - Institutional correspondence Carlos Robles Piquer's letter to Javier Tusell, dated 3 September
Madrid, 10 June 1981 - Internal institutional documents A letter from Carlos Robles Piquer to Javier Tusell
Paris, 1 March 1975 - Personal correspondence Claude Picasso's letter to William S. Lieberman, dated 1 March 1975