Baden-Baden, 1 July 1955 - Institutional correspondence A letter from the director of the Gesellschaft der Freunde junger Kunst Baden-Baden to the Musée des Arts Décoratifs
Zurich, 12 December 1955 - Institutional correspondence A letter from Klaus Herdeg to Willem Sandberg
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