Liber Sanguisugarum
The Liber Sanguisugarum (known as the Book of Blood but more accurately the Book of Leeches, or colloquially the book of parasites) was a book about the Mal'akh.
Commissioned in the 12th century by St. Bernard de Clairvaux, it was added to over the next several centuries. It contained early versions of the Book of Enoch and the Book of Noah, as well as an account by King Solomon of his imprisonment of a number of nephilim. Richard Francis Burton, one of the last contributors, said that it had all the information needed to fight the Mal'akh.
It was passed down through generations of the Grand Families. It was never rebound, yet always contained enough blank pages necessary to add new information. This implied it had a connection to the Great Houses, perhaps indicating a pact between the Families and the Houses.
For some of the 19th century, it was stored in Grindlay's Warehouse. It escaped destruction when the Warehouse was burned down because it was at the Ashmolean Library at the time.
Further examination of the book is unlikely as Burton took it with him to the Eleven-Day Empire when he joined Faction Paradox and access to it restricted. This could mean it contained things that might be not be in the best interests of the Faction. (PROSE: The Book of the War)