Madrid, 6 December 1968 - Institutional correspondence Luis Carrero Blanco's letter to Florentino Pérez Embid
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