Madrid, 2 December 1975 and Berkeley, California, 8 January 1976 - Institutional correspondence A letter from José Mario Armero to Herschel B. Chip, with reply
Madrid, 5 November 1980 - Institutional correspondence A letter from Íñigo Cavero to Blanche de Philip P. Weisberg (Blanche Mahler)
30 June 1981 - Institutional correspondence Letters from Íñigo Cavero to Pablo Picasso's heirs, dated 30 June 1981
Madrid, 13 June 1981 - Institutional correspondence Letters from Íñigo Cavero Pablo Picasso's heirs, dated 13 June 1981