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
30 October 1981 - Institutional correspondence John Koegel's letter to Richard E. Oldenburg, dated 30 October 1981
Sao Paulo, 25 March 1985 and Madrid, 2 April 1985 - Institutional correspondence The loan of Guernica denied for Brazil exhibition
New York, 31 August 1981 - Institutional correspondence John Koegel's letter to Richard E. Oldenburg, dated 31 August 1981