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
New York, 7 October 1953 - Institutional correspondence A letter from Letitia T. Howe to Pablo Picasso