Mexico, 21 December 1939 - Personal correspondence Juan Larrea's letter to Pablo Picasso, dated 21 December 1939
23 August 1939 - Internal museum documents Certificate of delivery for Guernica and other materials sent from the Spanish Refugee Relief Campaign to the San Francisco Museum of Art
Mexico, 4 October 1939 - Personal correspondence Juan Larrea's letter to Pablo Picasso, dated 4 October 1939