Bonn, 16 February 1956 - Institutional correspondence Antonio Mª Aguirre's letter to Alberto Martín-Artajo Álvarez
21 May 1976 - Personal correspondence Letter from Tomàs Llorens to Claude Picasso within the context of the Venice Biennale
New York, 20 October 1939 - Institutional correspondence Anne Beidberg's letter to Alfred H. Barr Jr.