Louis Réau. "Une collection de primitifs français en Amérique." Gazette des beaux-arts, 5th ser., 13 (January 1926), pp. 10–12, ill.
Louis Réau in Catalogue of a Loan Exhibition of French Primitives. Exh. cat., New York. New York, 1927, p. 124, no. 50, ill.
Louis Réau in The Michael Friedsam Collection. [completed 1928], pp. 155–56, calls it a Portrait of Charles IX by François Clouet and notes that Charles wears the collar of the order of Saint Michael; observes that the portrait reproduces exactly the type of the Vienna Museum's [Kunsthistorisches Museum] great Charles IX, of which the Louvre, Paris, has a reduced version; states [erroneously] that the model for these portraits is a drawing in the Hermitage Museum, St. Petersburg.
Bryson Burroughs and Harry B. Wehle. "The Michael Friedsam Collection: Paintings." Metropolitan Museum of Art Bulletin 27, section 2 (November 1932), p. 13, no. 8, ill. p. 12, comment that "whether by François Clouet or not, this portrait must occupy an honorable place in the group of paintings ascribed to him"; note that the drawing on which it is based (Cabinet des Estampes, Bibliothèque Nationale, Paris) is dated 1561, when Charles was eleven years old, the first year of his reign.
Katharine Grant Sterne. "The French Primitives in the Friedsam Collection." Parnassus 4 (January 1932), p. 9, ill. p. 7, attributes it to François Clouet and calls it a free variant of the portrait in Vienna.
Charles Sterling. "XV–XVIII Centuries." The Metropolitan Museum of Art: A Catalogue of French Paintings. 1, Cambridge, Mass., 1955, pp. 57–58, ill. p. 56, attributes it to a follower of François Clouet from the second half of the 16th century and calls it one of four contemporary portraits derived from Clouet's drawing of Charles IX in Paris and his painting of him in Vienna, both dated 1561; observes that our replica more closely follows the drawing in its half-length composition and in the form of the chain, and concludes that it was probably based on it rather than the Vienna painting.
"Vlamen, Holländer, Deutsche, Franzosen." Katalog der Gemäldegalerie. 2, Vienna, 1963, p. 31, lists our portrait and one in the Pinacoteca, Brescia [Pinacoteca Tosio-Martinengo], "among other repetitions" of Franços Clouet's half-length portrait of Charles in Vienna (no. 94).
Nancy H. Yeide et al. The AAM Guide to Provenance Research. Washington, 2001, pp. 51–52, 54, ill.
Everett Fahy in The Wrightsman Pictures. New York, 2005, p. 20, fig. 2.
Alexandra Zvereva. Portraits dessinés de la cour des Valois: Les Clouet de Catherine de Médicis. Paris, 2011, p. 365, under no. 395.