10 September 1981 - Internal museum documents Registration sheet for the Picasso works deposited at the Casón, including Guernica
1988-1992 - Internal museum documents Arranging the Collection: The transfer of Pablo Picasso's Guernica to the Centro de Arte Reina Sofía
New York, 31 August 1981 - Institutional correspondence John Koegel's letter to Richard E. Oldenburg, dated 31 August 1981