The Book of Kells manuscript is written on vellum — usually prepared by scraping calf skin — and spans 680 pages that experts think were written by at least three different monks.

Among the books, he discovered a manuscript apparently written in an unknown alphabet and decorated with more than 200 illustrations, half of which show unknown plants, figures and symbols.

The discovery was announced by the University of Cambridge on March 25. The manuscript is part of the Suite Vulgate du Merlin, a French-language rendering of the story of King Arthur.

Bolton's book, "The Room Where It Happened," will not be published until March 17. But on Sunday, The New York Times published a bombshell report based on the details of the unpublished manuscript.

A miniature unpublished manuscript written by Charlotte Brontë when she was 13 years old will go on sale for $1.25 million at a New York City book fair later this month. The work titled “A Book ...

The book was expected to sell for $2.6 million to $3.8 million. “This is the oldest known book in private hands, and at the same time one of the oldest books in existence,” Mr. Donadoni said.