Milan, 4 August 1953 - Institutional correspondence A letter from Fernanda Wittgens to Willem Sandberg, dated 4 August 1953
Milan, 12 August 1953 - Institutional correspondence Fernanda Wittgens' letter to Willem Sandberg, dated 12 August 1953
Milan, 7 October 1953 - Institutional correspondence A letter from Fernanda Wittgens to Willem Sandberg, dated 7 October 1953
November 23 - 24, 2011 - Conferences and articles Timothy J. Clark. Otra mirada al Guernica (Another look at Guernica)
6 September 1992 - Newspapers The Reina Sofía presents its Collection and becomes the century's museum of Spanish art