Zurich, 12 December 1955 - Institutional correspondence A letter from Klaus Herdeg to Willem Sandberg
Salamanca, 22 July 1981 - Institutional correspondence A letter from Mª Teresa Díez de los Ríos to Javier Tusell
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
Madrid, 8 February 1995 - Internal institutional documents A loan approval form for the exhibition Picasso: The Love and the Anguish. The road to Guernica