Stockholm, 23 October 1956 - Institutional correspondence Ernesto de Zulueta's letter to Alberto Martín-Artajo Álvarez
Madrid, 22 April 1976 - Internal institutional documents A report by Joaquín de la Puente on the ownership of Guernica and the negotiation possibilities with the Museum of Modern Art, New York
Madrid, 10 September 1981 - Internal museum documents Certificate for the reception of Guernica, and its stretcher and related works