Greene, Kevin (November 2007). Archaeology : An Introduction. University of Newcastle Upon Tyne. Chapter 4. Archived from the original on 2005-03-29. Retrieved 2008-01-04.
Greene, Kevin (November 2007). Archaeology : An Introduction. University of Newcastle Upon Tyne. Chapter 4. Archived from the original on 2005-03-29. Retrieved 2008-01-04.