Joseph Breck. "Sammlungen: Die Neuerwerbungen des Metropolitan Museum in New York." Der Cicerone 1 (1909), p. 292, attributes it to Bronzino.
B[ryson]. B[urroughs]. "Principal Accessions." Metropolitan Museum of Art Bulletin 4 (April 1909), p. 69, ill., attributes it to Bronzino.
Hanns Schulze. Die Werke Angelo Bronzinos. Strasbourg, 1911, p. XXIV, considers it a replica by Bronzino similar to the version in the Accademia in Florence.
Bryson Burroughs. Catalogue of Paintings. 3rd ed. New York, 1917, p. 32, as by Bronzino.
Arthur McComb. Agnolo Bronzino, His Life and Works. Cambridge, Mass., 1928, pp. 13, 72–73, pl. 17, calls this portrait probably the original, and dates it about 1542–45.
Harry B. Wehle. The Metropolitan Museum of Art: A Catalogue of Italian, Spanish, and Byzantine Paintings. New York, 1940, p. 69, ill.
Luisa Becherucci. Manieristi toscani. Bergamo, 1944, p. 42, mentions it among the replicas of the Uffizi portrait, which she feels is the original.
Andrea Emiliani. Il Bronzino. Busto Arsizio, 1960, unpaginated, opp. pl. 90, calls it a replica of the Uffizi portrait.
Federico Zeri with the assistance of Elizabeth E. Gardner. Italian Paintings: A Catalogue of the Collection of The Metropolitan Museum of Art, Florentine School. New York, 1971, p. 203, ill., call it probably derived from a Bronzino portrait of Cosimo I de' Medici painted in 1545 (now possibly no. 28 in the Uffizi); mention fringed curtain and ornamental border probably taken from the "Portrait of a Man" by Salviati (MMA 55.14).
Burton B. Fredericksen and Federico Zeri. Census of Pre-Nineteenth-Century Italian Paintings in North American Public Collections. Cambridge, Mass., 1972, pp. 36, 515, 605.
Edi Baccheschi. L'opera completa del Bronzino. Milan, 1973, p. 94, no. 54g, considers it a workshop version of the Uffizi portrait.
Robert Barry Simon. "Bronzino's Portraits of Cosimo I de' Medici." PhD diss., Columbia University, 1982, pp. 91–93, 260–63, no. A21, notes that it is the work of a copyist whose model must have been a half-length rather than a three-quarter-length portrait, dates it 1543–44, and thinks that the hanging in the background derives from another composition (cites our "Portrait of a Young Man" by Salviati [45.128.11]) and alludes to hangings that covered portraits in the Cinquecento.
Robert B. Simon. "Bronzino's Portrait of Cosimo I in Armour." Burlington Magazine 125 (September 1983), pp. 528, 531–32, 539, no. 21, fig. 10, discusses the numerous versions of this portrait (over 25 examples are listed in his Appendix II) and considers our version to be by "an artist other than Bronzino".
Angela Tamvaki in El Greco in Italy and Italian Art. Exh. cat., National Gallery Alexandros Soutzos Museum. Athens, 1995, pp. 266–68, 490, ill.
Antonio Geremicca in Bronzino: Artist and Poet at the Court of the Medici. Exh. cat., Palazzo Strozzi. Florence, 2010, p. 114.
Alejandra González Leyva in Manierismo: El Arte después de la Perfección. Exh. cat., Museo Nacional de San Carlos. Mexico City, 2014, p. 56, fig. 2 (color).