New York, 12 March 1956 - Institutional correspondence Bernard Karpel's letter to Willem Sandberg, dated 12 March 1956
New York, 27 November 1956 - Institutional correspondence Bernard Karpel's letter to Willem Sandberg, dated 27 November 1956
April, 1980 (original from 1957) - Magazines The Picasso Summer. He could say the man's name once, in a whisper, to himself