Amsterdam, 18 January 1956 - Transport documents Hans Ludwig Cohn Jaffé's letter to Holland-Amerika Lijn
Amsterdam, 17 October 1956 - Institutional correspondence A letter from Hans Ludwig Cohn Jaffé's to the editors of the newspaper De Tijd
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