20 February 1980 - Institutional correspondence A letter from Ricardo de la Cierva Hoces to Adolfo Suárez
Madrid, 28 June 1980 - Institutional correspondence Ricardo de la Cierva Hoces' letter to Javier Tusell
Stockholm, 27 October and 1 de November 1956 - Institutional correspondence Memos of Swedish Foreign Ministry about the catalogue and exhibition Guernica