Nennius' Wonders of Britain - Geographer Andy Evans traces a list of natural wonders attributed, traditionally, to the monk Nennius, and written around 829. - http://www.wondersofbritain.org
Historia Britonum - Latin text of Nennius's history of the British people, from Six Old English Chronicles, edited by J. A. Giles. - http://www.fordham.edu/halsall/basis/nennius-full.html