Carter, Robert A. and Philip, Graham Beyond the Ubaid: Transformation and Integration in the Late Prehistoric Societies of the Middle East (Studies in Ancient Oriental Civilization, Number 63) The Oriental Institute of the University of Chicago (2010) பன்னாட்டுத் தரப்புத்தக எண்978-1-885923-66-0 p.2, at http://oi.uchicago.edu/research/pubs/catalog/saoc/saoc63.htmlபரணிடப்பட்டது 2013-11-15 at the வந்தவழி இயந்திரம்; "Radiometric data suggest that the whole Southern Mesopotamian Ubaid period, including Ubaid 0 and 5, is of immense duration, spanning nearly three millennia from about 6500 to 3800 B.C".
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Carter, Robert A. and Philip, Graham Beyond the Ubaid: Transformation and Integration in the Late Prehistoric Societies of the Middle East (Studies in Ancient Oriental Civilization, Number 63) The Oriental Institute of the University of Chicago (2010) பன்னாட்டுத் தரப்புத்தக எண்978-1-885923-66-0 p.2, at http://oi.uchicago.edu/research/pubs/catalog/saoc/saoc63.htmlபரணிடப்பட்டது 2013-11-15 at the வந்தவழி இயந்திரம்; "Radiometric data suggest that the whole Southern Mesopotamian Ubaid period, including Ubaid 0 and 5, is of immense duration, spanning nearly three millennia from about 6500 to 3800 B.C".