Hadrian, the first emperor to wear a beard, introduced the style to fashionable Roman circles. The sword belt and military cloak, worn over a bare chest, are frequent attributes in Trajanic portraiture and suggest that this is a transitional likeness from the beginning of Hadrian's reign.
Richter, Gisela M. A. 1914. "Department of Classical Art Accessions 1913." Bulletin of the Metropolitan Museum of Art, 9 (3): pp. 62-3, fig. 6.
Richter, Gisela M. A. 1941. Roman Portraits, Vol. 2. New York: The Metropolitan Museum of Art.
Richter, Gisela M. A. 1948. Roman Portraits, 2nd edn. no. 57, p. iv, New York: The Metropolitan Museum of Art.