G. C. Williamson, 'Mr J. Pierpont Morgan's Pictures. The Early Miniatures', I, The Connoisseur, December 1906, vol. XVI, p. 206, no. XVI, (as Robert, Earl of Essex by Isaac Oliver).
G. C. Williamson, Catalogue of the Collection of Miniatures. The Property of J. Pierpont Morgan, London, 1907, I, p. 52, no. 44, illustrated pl. XIV, fig. 3 (as Robert Devereux, Earl of Essex by Isaac Oliver).