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
28 February 1974 - Press release and communication The artist Tony Shafrazi has freed Guernica from its chains of ownership and has returned its revolutionary nature
Ellen C. Oppler (ed.), <em>Picasso’s Guernica</em>, New York and London: W. W. Norton & Company, 1988, 236–238 - Essay “How Effective Is Social Protest Art? (Vietnam)”
Siracusa, New York, 15 July 1979 - Institutional correspondence Ellen Oppler's letter to Luisa Kreisberg