Amsterdam, 6 July 1956 - Institutional correspondence A letter from J. M. Trias de Bes to Alberto Martín-Artajo Álvarez
1992-1993 - Internal museum documents Exhibition folder. Picasso: The Love and the Anguish. The Road to Guernica
New York, 22 February 1979 - Institutional correspondence Michael Blackwood's letter to Louise Kreisberg