Apolodorus and others indicate that he had three heads, but Hesiod with poetical hyperbole gives him fifty. Elton, Charles Abraham (1812). Hesiod, translated from the Greek into English verse, with a Preliminary Dissertation on the Writings, Life, and Γra of Hesiod. London: Lackington, Allen and Company. p. 267.
Geri and Freki, "Greedy" and "Voracious" Bloomfield, Maurice (1905). Cerberus, the Dog of Hades: The History of an Idea. Open Court Publishing. pp. 26β27.