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
1939 - Institutional correspondence Acceptance letters from Alfred H. Barr Jr., Aleksina Matisse, Georgia O'Keefe and Sidney Janis to Caspar Whitney