Carl Frederik Wilckens: Træk af Thorvaldsens Konstner- og omgangsliv, samlede til Familielæsning, Copenhagen 1874, p. 45. Wilckens assumes incorrectly that Drejer, who was Løffler’s son-in-law, gave Thorvaldsen the medallion.
Else Kai Sass: Thorvaldsens Portrætbuster, Copenhagen 1963, Vol. I, p. 26-31. The original model, A864, was donated to the museum in 1926 by the sculptor, Professor E. Utzon-Frank.