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
Stockholm, 27 October and 1 de November 1956 - Institutional correspondence Memos of Swedish Foreign Ministry about the catalogue and exhibition Guernica