Brussels, 6 September 1957 - Institutional correspondence Émile Langui's letter to Pablo Picasso, dated 6 September 1957
New York, 30 May 1957 - Institutional correspondence Alfred H. Barr Jr.'s letter to Daniel-Henry Kahnweiler, dated 30 May 1957
New York, 16 February 1957 - Institutional correspondence Alfred H. Barr Jr.'s letter to Pablo Picasso, dated 16 February 1957
Paris, 17 April 1957 - Institutional correspondence A telegram from Daniel-Henry Kahnweiler to Alfred H. Barr Jr.
New York, 16 January 1957 - Institutional correspondence Alfred H. Barr Jr.'s letter to Roland Penrose, dated 16 January 1957