New York, 14 April 1967 - Institutional correspondence Alfred H. Barr Jr.'s letter to Daniel-Henry Kahnweiler, dated 14 April 1967
New York, 27 February 1970 - Personal correspondence A letter from Meyer Schapiro to Alfred H. Barr Jr.
Paris, 18 April 1953 - Personal correspondence Daniel-Henry Kahnweiler's letter to Pablo Picasso, dated 18 April 1953
New York, 23 March 1981 - Internal museum documents An internal letter from New York's Museum of Modern Art on the 1974 attack on Guernica
Paris, April 20, 1967 - Letter Daniel-Henry Kahnweiler's letter to Alfred H. Barr Jr., dated 20 April 1967