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
1939 - Institutional correspondence Acceptance letters from Alfred H. Barr Jr., Aleksina Matisse, Georgia O'Keefe and Sidney Janis to Caspar Whitney
New York, 22 November 1969 - Institutional correspondence A letter from William S. Lieberman to Roland Dumas
New York, 7 March 1956 - Institutional correspondence William S. Lieberman's letter to Porter McCrary
New York, 20 September 1956 - Institutional correspondence William S. Lieberman's letter to Alfred H. Barr Jr.
New York, 7 June 1977 - Institutional correspondence William S. Lieberman's letter to Richard Oldenburg, dated 7 June 1977
New York, 1 June 1977 - Institutional correspondence William S. Lieberman's letter to Richard Oldenburg, dated 1 June 1977
New York, 31 May 1977 - Institutional correspondence William S. Lieberman's letter to Richard Oldenburg, dated 31 May 1977
New York, 5 July 1956 - Institutional correspondence William S. Lieberman's letter to Richard Griffith