Caxton Watermark QA #12, from Sotheby, Samuel L. Principia Typographica: An Extensively Illustrated Work in Three Volumes, Imperial Quarto, on the Block-Books, Xylographic Delineations of Scripture History Issued in Holland, Flanders, and Germany During the Fifteenth Century: on Their Connexion with the Origin of Printing and on the Character of Water-Marks in the Paper of the Period  . 3 vols. London: 1858. (Volume 3: "Paper-Marks")