Amsterdam, 16 November 1953 - Institutional correspondence Willem Sandberg's letter to Pablo Picasso, dated 16 November 1953
Amsterdam, 8 November 1955 - Institutional correspondence Willem Sandberg's letter to Josep Lluís Sert
Amsterdam, 11 October 1955 - Institutional correspondence Willem Sandberg's letter to Daniel-Henry Kahnweiler, dated 11 October 1955
Amsterdam, 8 November 1955 - Institutional correspondence Willem Sandberg's letter to Alexander Calder, dated 8 November 1955
Amsterdam, 30 November 1955 - Institutional correspondence Willem Sandberg's letter to Alexander Calder, dated 30 November 1955
Amsterdam, 2 December 1955 - Personal correspondence Willem Sandberg's letter to Maurice Lefebvre-Foinet, dated 2 December 1955
Amsterdam, 3 December 1955 - Institutional correspondence Willem Sandberg's letter to Dora Maar, dated 3 December 1955
Amsterdam, 9 December 1955 - Personal correspondence Willem Sandberg's letter to Maurice Lefebvre-Foinet, dated 9 December 1955
Amsterdam, 16 December 1955 - Institutional correspondence Willem Sandberg's letter to Dora Maar, dated 16 December 1955
Amsterdam, 27 December 1955 - Institutional correspondence Willem Sandberg's letter to l'Association Française d'Action Artistique
Amsterdam, 21 March 1956 - Institutional correspondence Willem Sandberg's letter to Robert Giron, dated 21 March 1956
Amsterdam, 4 April 1956 - Institutional correspondence Willem Sandberg's letter to Robert Giron, dated 4 April 1956
Amsterdam, 11 April 1956 - Institutional correspondence Willem Sandberg's letter to Robert Giron, dated 11 April 1956
Amsterdam, 11 January 1956 - Transport documents Willem Sandberg's letter to Holland-Amerika Lijn, dated 11 January 1956
Amsterdam, 11 January 1956 - Institutional correspondence Willem Sandberg's letter to Robert Giron, dated 11 January 1956
Amsterdam, 23 January 1956 - Institutional correspondence Willem Sandberg's letter to Alexander Calder, dated 23 January 1956
Amsterdam, 21 February 1956 - Transport documents Willem Sandberg's letter to Holland-Amerika Lijn, dated 21 February 1956
Amsterdam, 24 February 1956 - Institutional correspondence Willem Sandberg's letter to Bernard Karpel, dated 24 February 1956
Amsterdam, 25 February 1956 - Transport documents Willem Sandberg's letter to Holland-Amerika Lijn, dated 25 February 1956
Amsterdam, 27 February 1956 - Institutional correspondence Willem Sandberg's letter to Amsterdam City Council, dated 27 February 1956
