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
14 June 1997 - Newspapers The PNV (Basque Nationalist Party) secures a commitment from the PP (People's Party) for the temporary transfer of "Gernika" to Bilbao