New York, 16 December 1954 - Institutional correspondence A letter from Alfred H. Barr Jr. to William A. M. Burden, René d'Harnoncourt and James Thrall Soby
New York, 11 June 1957 - Institutional correspondence Alfred H. Barr Jr.'s letter to René d'Harnoncourt, dated 11 June 1957
New York, 10 July 1954 - Institutional correspondence A letter from Alfred H. Barr Jr. to René d'Harnoncourt, dated 10 July 1954
