Paris, 21 December 1955 - Personal correspondence Daniel-Henry Kahnweiler's letter to Pablo Picasso, dated 21 December 1955
Paris, 13 April 1956 - Personal correspondence Daniel-Henry Kahnweiler's letter to Pablo Picasso, dated 13 April 1956
Philadelphia, 18 September 1957 - Institutional correspondence Henry Clifford's letter to Pablo Picasso