New York, 9 July 1956 - Institutional correspondence Alfred H. Barr Jr.'s letter to Pablo Picasso, dated 9 July 1956
Amsterdam, 22 May 1956 - Institutional correspondence Willem Sandberg's letter to Pablo Picasso, dated 22 May 1956
New York, 31 March 1956 - Institutional correspondence Alfred H. Barr Jr.'s letter to Pablo Picasso, dated 31 March 1956
New York, 12 May 1956 - Institutional correspondence Alfred H. Barr Jr.'s letter to Pablo Picasso, dated 12 May 1956