Mexico City, 26 September 1968 - Institutional correspondence A letter from Rachmael ben Avram to Nelson Rockefeller
Mexico City, 26 September 1968 - Institutional correspondence Rachmael ben Avram's letter to Carol K. Uht
Madrid, 29 May and 10 June 1981 - Institutional correspondence A letter from Felipe Cons Gorostola to Álvaro Martínez Novillo, and reply