Stockholm, 23 October 1956 - Institutional correspondence Ernesto de Zulueta's letter to Alberto Martín-Artajo Álvarez
Paris, 10 December 1975 - Institutional correspondence Miguel de Lojendio's letter to Spain's Ministry of Culture
1 December 1945 - Institutional correspondence Claude Jaeger's letter to Pablo Picasso with an enclosed letter from Celeste Negarville