Flushing, New York, 23 May 1939 - Institutional correspondence Simon Guggenheim's and Dana C. Backus's form letter to ask for donations
Paris, 28 March 1939 - Personal correspondence Pablo Picasso's letter to Roland Penrose, dated 28 March 1939
New York, 1939 - Exhibition catalogue Catalogue of the exhibition organised by the American Artists' Congress at the Valentine Gallery, for the benefit of Spanish refugees. Signed by Juan Negrín and Julio Álvarez del Vayo
