Oscar Hainauer [d. 1894], Berlin; his wife, Julie Hainauer, Berlin; acquired 1906 by (Duveen Brothers, Inc., London and New York); by exchange 21 October 1920 to Joseph E. Widener, Lynnewood Hall, Elkins Park, Pennsylvania; gift 1942 to NGA.
- Bode, Wilhelm von, ed. Die Sammlung Oscar Hainauer / The Collection of Oscar Hainauer. [bound as one volume, English and German pages interleaved in one page sequence] Berlin, 1897 and London, 1906: 92, no. 197 (Plaquette no. 57), as Floratius (sic) Cocles, by “Giovanni Fiorentino” [that is, Master IO.F.F.].
- A Cabinet of One Hundred & Thirty-Three Bronze Plaques and Medals of the Renaissance Period from the Collection of the Late Herr Oscar Hainauer of Berlin. Ed. Duveen Brothers. London, n.d. (but 1908): no. 112, repro.
- Works of Art from the Widener Collection. Foreword by David Finley and John Walker. National Gallery of Art, Washington, 1942: 15.
- Fulton, Christopher B. "The Master IO.F.F. and the Function of Plaquettes." Studies in the History of Art 22 (1989): 147, 159 note 13, fig. 7, as by Master IO.F.F.
- Rossi, Francesco. La collezione Mario Scaglia: placchette. 3 vols. Bergamo, 2011: 1:275, under Prototipo, M.12, and C.7, as part of the Hainauer Collection.