Necronomicon

in Latin, written by Olaus Wormius, 1228 A.D.

One of four copies known to survive from a Spanish Edition in the seventeenth century. Wormius' translation of the Greek original lacks the star charts and astrological data associated with the earlier versions, but this does little to diminish its value as the ultimate repository of mythos knowledge. The work touches upon every aspect of the Cthulhu mythos. (Johnson, Sam, and Sandy Antunes. "Miskatonic University: A Handbook to the Pride of Arkham." Chaosium, Oct. 2005.)
First circulated in manuscript form, then printed in Germany in the late 15th century as a black-letter folio. A second, nearly identical edition was published in Spain in the early 17th century. One copy of the former edition is known to still exist. (Petersen, Sandy, and H. P. Lovecraft. Call of Cthulhu Keeper Rulebook Horror Roleplaying in the Worlds of H.P. Lovecraft. Chaosium, Inc., 2016.)
The version of the tome that resides in the Miskatonic University Library was part of the original Jerimiah Orne bequest, and is easily the most famous book in the collection.