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
Madrid, 31 July, and Cambridge, Massachusetts, 31 August 1981 - Institutional correspondence Álvaro Martínez Novillo's letter to Josep Lluís Sert, with reply
Madrid, 29 May and 10 June 1981 - Institutional correspondence A letter from Felipe Cons Gorostola to Álvaro Martínez Novillo, and reply
New York, 3 September 1981 - Internal institutional documents Inventory and conservation report on the works collected by New York's Museum of Modern Art to be sent to Spain
Madrid, 8 February 1982 - Institutional correspondence A letter from Álvaro Martínez Novillo to Pedro J. Ramírez
New York, 8 September 1981 - Internal institutional documents A confidential and private document signed by Álvaro Martínez-Novillo and José María Cabrera in New York