Sao Paulo, 25 March 1985 and Madrid, 2 April 1985 - Institutional correspondence The loan of Guernica denied for Brazil exhibition
Paris, 2 November 1979 - Personal correspondence A copy of a letter Claude Picasso wrote to William Rubin, director of Painting and Sculpture at MoMA
Paris, 1 March 1975 - Personal correspondence Claude Picasso's letter to William S. Lieberman, dated 1 March 1975