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
Madrid, 10 September 1981 - Internal museum documents Certificate for the reception of Guernica, and its stretcher and related works