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 - Institutional correspondence Willem Sandberg's letter to Robert Giron, dated 11 January 1956
Amsterdam, 27 February 1956 - Institutional correspondence Willem Sandberg's letter to Amsterdam City Council, dated 27 February 1956
Amsterdam, 4 May 1956 - Institutional correspondence Willem Sandberg's letter to Robert Giron, dated 4 May 1956