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
8 May 2017 - Concert After Guernica. A Sinfonietta by the Reina Sofía Music School, conducted by Baldur Brönnimann
ca. 1952–1956 - Internal museum documents Publicity report for the exhibition Studies for Guernica by the University of Minnesota Gallery, addressed to the Travelling Exhibitions Department at the Museum of Modern Art, New York