Stockholm, 23 October 1956 - Institutional correspondence Ernesto de Zulueta's letter to Alberto Martín-Artajo Álvarez
New York, 10 July 1939 - Institutional correspondence Blanche Mahler's letter to Grace L. McCann Morley
2 May 1939 - Internal institutional documents A draft text for the invitation to the exhibition Picasso's Guernica at the Valentine Gallery, New York