New York, 6 May 1955 - Institutional correspondence A letter from W.R. Keating & Company International to R. Lerondelle
New York, 23 January 1957 - Transport documents A letter from the vice-president of W. R. Keating & Company to Willem Sandberg
New York, 22 April 1960 - Institutional correspondence A letter from Jan-Albert Goris to Nelson Rockefeller, dated 22 April 1960
New York, 25 April 1960 - Institutional correspondence Jan-Albert Goris's letter to Nelson Rockefeller, dated 25 April 1960