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
Madrid, 19 June 1981 - Institutional correspondence A letter from Carlos Robles Piquer to Javier Tusell, dated 19 June 1981
<em>The New York Times</em>, New York, November 11, 1990, 1, 39 - Article “When Picasso Spooked the FBI”