8 July 1937 - Institutional correspondence Paul P. Rogers' letter to the North American Committee to Aid Spanish Democracy
12 September 1981 - Newspapers Protests in the Basque Country over the installation of Guernica in the Casón del Buen Retiro
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