{"id":"000871471","type":"article","title":"Varieties and Sources of Artefactual Obsidian in the Middle Stone Age of the Middle Awash, Ethiopia","publisher":"Oxford University, Research Laboratory for Archaeology and the History of Art","publisher-place":"Oxford","pages":"661-673","container-title":"Archaeometry, 53,4 (2011","author":[{"family":"Negash","given":"Agazi"}],"issued":{"raw":"2011"}}