The sources of the book, which include various authors besides those included in this article specified, have been laboriously investigated by Albert Bovenschen and George F. Warner. The oldest known manuscript of the original—once Jean-Baptiste-Joseph Barrois's, afterwards Bertram Ashburnham, 4th Earl of Ashburnham's, now "Nouv. Acq. Franc. 1515" in the Bibliothèque nationale de France—is dated 1371, but is nevertheless very inaccurate in proper names. An early printed Latin translation made from the French has been already quoted, but four others, unprinted, have been discovered by Dr Johann Vogels. They exist in eight manuscripts, of which seven are in Great Britain, while the eighth was copied by a monk of Abingdon; probably, therefore, all these unprinted translations were executed in Great Britain.