Madrid, 8 July 1972 - Institutional correspondence A letter from Xavier de Salas to Florentino Pérez Embid
1988-1989 - Institutional correspondence Correspondence related to the Guernica exhibition project at the Museum Boymans-van Beuningen in Rotterdam
New York: Praeger Publishers Inc., 1973 - Essay Six Years: The Dematerialization of the Art Object from 1966 to 1972