found: Work cat.: Tell al-ʻAbr, Syria : Ubaid and Uruk periods, 2006.
found: Encyclopedia of world history, 2001, viewed online, Mar. 7, 2006(Uruk culture, c. 3500-3100 BC; a Sumerian/Akkadian culture)
found: Wikipedia, Mar. 7, 2006(Uruk period, ca 4000-3100 BC, is the protohistoric Chalcolithic to Early Bronze Age period in the history of Mesopotamia, following the Ubaid period; named after the city of Uruk, this period saw the emergence of urban life in Mesopotamia; followed by the Sumerian civilization)
found: Areshian, G.E. Further thoughts on the Uruk expansion, in Current anthropology, v. 31, no. 4, viewed online, Mar. 7, 2007(Ubaid and Uruk periods in Mesopotamia)
