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
Paris, 30 October 1971 - Institutional correspondence A letter from Luis López Ballesteros to Alfredo Sánchez Bella