Necronomicon: This is the title of the book Noel Evans (Bill Bixby) was hired to translate. It was the creation of H.P. Lovecraft and formed one of the centerpieces of his Cthulhu Mythos stories. "Written" by the "mad Arab" Abdul Alhazred, it is described as a "terrible and forbidden" volume.
A number of Lovecraft's colleagues, proteges and successors, with his approval, borrowed from and expanded upon elements of his works, including the Necronomicon. Among these are August Derleth (manager of Lovecraft's literary estate), Robert Bloch (author of Psycho and Clark Ashton Smith, the author of the story from which this episode was adapted.
The book also featured prominently in director Sam Raimi's Evil Dead series of films.