New York, 9 September 1981 - Institutional correspondence An internal letter from Richard E. Oldenburg to staff at the Museum of Modern Art, New York
New York, 24 March 1980 - Institutional correspondence A letter from Richard Oldenburg and William Rubin to Javier Tusell
New York, 28 April 1977 - Internal institutional documents Conversation between José Mario Armero and William Rubin
Madrid, 17 September 1980 - Institutional correspondence A letter from José Mario Armero to Íñigo Cavero