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
Farmington, Connecticut, 20 September 1946 - Personal correspondence James Thrall Soby's letter to William Lieberman
Madrid, 19 June 1981 - Institutional correspondence A letter from Carlos Robles Piquer to Javier Tusell, dated 19 June 1981