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, April 20, 1967 - Letter Daniel-Henry Kahnweiler's letter to Alfred H. Barr Jr., dated 20 April 1967