. . . The Book of Eibon, that strangest and rarest of occult forgotten volumes ... is said to have come down through a series of manifold translations from a prehistoric original written in the lost language of Hyperborea.
—Clark Ashton Smith, "Ubbo-Sathla"
The Book of Eibon, or Liber Ivonis or Livre d'Eibon, is attributed to Clark Ashton Smith. It appears in a number of Lovecraft's stories, such as "The Haunter Of The Dark" (Liber Ivonis), "Dreams in the Witch-House" (Book of Eibon) and "The Shadow Out of Time" (Book of Eibon).