Skelly, Robert, Anne Ford, Glenn Summerhayes, Jerome Mialanes, and Bruno David. 2016. “Chemical Signatures & Social Interactions: Implications of West Fergusson Island Obsidian at Hopo, East of the Vailala River (Gulf of Papua), Papua New Guinea”. Journal of Pacific Archaeology 7 (1), 126-38. https://pacificarchaeology.org/index.php/journal/article/view/186.