Paris, 29 September 1955 - Institutional correspondence Daniel-Henry Kahnweiler's letter to Willem Sandberg, dated 29 September 1955
Amsterdam, 11 October 1955 - Institutional correspondence Willem Sandberg's letter to Daniel-Henry Kahnweiler, dated 11 October 1955
Paris, 22 May 1956 - Institutional correspondence Daniel-Henry Kahnweiler's letter to Willem Sandberg, dated 22 May 1956
Amsterdam, 23 May 1956 - Institutional correspondence Willem Sandberg's letter to Daniel-Henry Kahnweiler, dated 23 May 1956