Roxbury, 22 November 1955 - Institutional correspondence Alexander Calder's letter to Willem Sandberg, dated 22 November 1955
Roxbury, 12 January 1956 - Institutional correspondence Alexander Calder's letter to Willem Sandberg, dated 12 January 1956
Report, La Sexta Noticias, January 21, 2016 - News programme “Declarados culpables de fiasco económico los gestores de la ‘Bienal de arte’ de Sevilla” (The managers of the Art Biennial of Seville found guilty of a “financial fiasco”)