^Snyder, James (1985). Northern Renaissance Art: Painting, Sculpture, the Graphic Arts from 1350 to 1575. New York: Harry N. Abrams. p. 486. ISBN0-8109-1081-0.
^Pallucchini, Anna; Ragghianti, Carlo Ludovico; Collobi, Licia Ragghianti (1968). Prado, Madrid. Great Museums of the World. New York: Newsweek. p. 134.