New York, 16 October 1981 - Institutional correspondence John Koegel's letter to Javier Tusell, dated 16 October 1981
New York, 16 October 1981 - Institutional correspondence John Koegel's letter to Javier Tusell, dated 16 October 1981
New York, 16 October 1981 - Institutional correspondence John Koegel's letter to Javier Tusell, dated 16 October 1981
Madrid, 15 March 1986 - Institutional correspondence Letter from Alfonso E. Pérez Sánchez to Dionisio Hernández Gil
New York and Madrid, June 1988 - Institutional correspondence Correspondence between William Rubin and Alfonso E. Pérez Sánchez
New York, 31 August 1981 - Institutional correspondence John Koegel's letter to Richard E. Oldenburg, dated 31 August 1981