New York, 12 March 1956 - Institutional correspondence Bernard Karpel's letter to Willem Sandberg, dated 12 March 1956
New York, 27 November 1956 - Institutional correspondence Bernard Karpel's letter to Willem Sandberg, dated 27 November 1956
12 September 1981 - Newspapers Protests in the Basque Country over the installation of Guernica in the Casón del Buen Retiro