Ballin, Torben Bjarke. “The Worked Quartz Vein at Cnoc Dubh, Uig Parish, Isle of Lewis, Western Isles: Presentation and Discussion of a Small Prehistoric Quarry”. Scottish Archaeological Internet Reports, vol. 11, Jan. 2004, pp. 1-23, doi:10.9750/issn.2056-7421.2004.11.1-23.