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
Madrid, 10 September 1981 - Internal museum documents Certificate for the reception of Guernica, and its stretcher and related works
Chicago, 11 October 1939 - Institutional correspondence Charles Goodspeed's telegram to Pablo Picasso
Gerti Fietzek (ed.), Cologne: Buchhandlung Walther König, 2009 - Essay Maria Eichhorn. The Artist's Contract