Madrid, 22 April 1976 - Internal institutional documents A report by Joaquín de la Puente on the ownership of Guernica and the negotiation possibilities with the Museum of Modern Art, New York
Madrid, 10 September 1981 - Internal museum documents Certificate for the reception of Guernica, and its stretcher and related works
<em>Newsweek</em>, New York, March 10, 2015 - Article “Mark Lombardi's Art Was Full of Conspiracies — Now His Death Has Become One”