Jelaskan Catatan dari Geri dan Freki

Bloomfield, Maurice (1908) "Cerberus" in: Hastings, James (Ed.) Encyclopaedia of Religion and Ethics, Vol. 5. Edinburgh: T. & T. Clark.

Grimm, Jacob (1882). Teutonic Mythology, Vol. I, Translated from the 4th Edition by James Steven Stallybrass. London: George Bell & Sons.

Spiedel, Michael (2004). Ancient Germanic Warriors: Warrior Styles from Trajan's Column to Icelandic Sagas. Routledge.

Thorpe, Benjamin (Trans) (1907). Edda Sæmundar Hinns Frôða The Edda of Sæmund the Learned. Part I. London Trübner & Co