Roxbury, 22 November 1955 - Institutional correspondence Alexander Calder's letter to Willem Sandberg, dated 22 November 1955
Roxbury, 12 January 1956 - Institutional correspondence Alexander Calder's letter to Willem Sandberg, dated 12 January 1956
1992-1993 - Internal museum documents Exhibition folder. Picasso: The Love and the Anguish. The Road to Guernica
May - July 1992 - Institutional correspondence Loaned works at the Museo Nacional Centro de Arte Reina Sofía in conjunction with the rearrangement of holdings between the Reina Sofía and Museo Nacional del Prado