Flushing, New York, 23 May 1939 - Institutional correspondence Simon Guggenheim's and Dana C. Backus's form letter to ask for donations
Madrid, 30 March 1988 - Internal institutional documents A letter from the director-general of Fine Arts to the Cabinet of Spain's Ministry of Culture
Madrid, 14 September 1981 - Institutional correspondence Official notice from the Management Board of Fine Arts, Archives and Museums to José Manuel Pita Andrade