Maurice W. Brockwell. Antonis Mor, (Dutch School. 1519–1576), Portrait of Ottavio Farnese, Second Duke of Parma. (1524–1586) [produced for Knoedler Galleries]. 1920, identifies the sitter as Ottavio Farnese, comparing it with a portrait of Ottavio which he ascribes to Girolamo Mazzuola di Parma [now Museo Nazionale di Capodimonte, Naples] and with medals of him executed by Pastorino between 1552 and 1556; comments on the resemblance of pose and character between our portrait and the Portrait of a Young Man, which he identifies as Alessandro Farnese, the son of Ottavio, by Sanchez Coello, a pupil of Anthonis Mor [now National Gallery of Ireland, Dublin].
"Current Art Notes." Connoisseur 74 (February 1926), p. 121, ill. opp. p. 116, illustrate it as a portrait of a gentleman by Mor.
Paul Lambotte. "Exhibition of Flemish and Belgian Art, Copenhagen." Apollo 13 (June 1931), p. 381.
Max J. Friedländer. Die altniederländische Malerei. Vol. 13, Anthonis Mor und seine Zeitgenossen. Leiden, 1936, p. 173, no. 374, pl. 70, lists it with the works of Mor and illustrates it as "Ottavio Farnese (?)".
Francis M. Kelly. "On a Portrait at Buckingham Palace." Connoisseur (December 1940), p. 185, ill., as Ottovavio Farnese by "Ant. Mor?".
L. C. J. Frerichs. Antonio Moro. Amsterdam, , p. 42, ill. opp. p. 45.
Max J. Friedländer et al. Early Netherlandish Painting. Vol. 13, Antonis Mor and His Contemporaries. New York, 1975, p. 103, no. 374, pl. 184.
Margrit A. Jay. "Antonio Moro: Royal Court Painter, 1519–1576." PhD diss., Texas Christian University, 1975, p. 119, lists it under the heading "Paintings Attributed to Moro: Doubtful".
From Van Eyck to Bruegel: Early Netherlandish Painting in The Metropolitan Museum of Art. Ed. Maryan W. Ainsworth and Keith Christiansen. Exh. cat., The Metropolitan Museum of Art. New York, 1998, p. 411, ill.