2 March 1974 - Institutional correspondence A letter from Karl Denim, S. S. Kush and Joshua Jericho in defence of Tony Shafrazi
Amsterdam, 6 July 1956 - Institutional correspondence A letter from J. M. Trias de Bes to Alberto Martín-Artajo Álvarez
Princeton, 8 December 1956 - Institutional correspondence A letter from Kazuko Higuchi to Alfred H. Barr Jr.