Milan, 4 August 1953 - Institutional correspondence A letter from Fernanda Wittgens to Willem Sandberg, dated 4 August 1953
Milan, 12 August 1953 - Institutional correspondence Fernanda Wittgens' letter to Willem Sandberg, dated 12 August 1953
Milan, 7 October 1953 - Institutional correspondence A letter from Fernanda Wittgens to Willem Sandberg, dated 7 October 1953
New York, 8 May 1956 - Institutional correspondence Carol K. Uht's letter to Petro (Nelly) Van Doesburg
New York, 9 April 1963 - Institutional correspondence Carol K. Uht's letter to Nelson Rockefeller, dated 9 April 1963
New York, 27 August 1968 - Internal institutional documents Carol K. Uht's letter to Nelson Rockefeller, dated 27 August 1968
New York, 24 March 1969 - Institutional correspondence Carol K. Uht's letter to Nelson Rockefeller, dated 24 March 1969
New York, 30 April 1969 - Institutional correspondence Carol K. Uht's letter to Richard Gordon Hatche
ca. 1952–1956 - Internal museum documents Publicity report for the exhibition Studies for Guernica by the School of Fine and Applied Arts, Columbus, Ohio, addressed to the Travelling Exhibitions Department at the Museum of Modern Art, New York