 Fimbulwinter, the magically-induced winter weather that hinders the children's escape, also refers to Norse eschatology.Other terms are taken not from Norse mythology, but from the Welsh mythology encapsulated in Mediaeval texts like the "Mabinogion".For instance, Govannon, one of the names with which Garner addresses Grimnir, has been adopted from the mythological character of Govannon ap Dun.