Ur-Nammu was the first king of the Sumerian Third Dynasty of Ur. He helped restore native dominance in Sumer after centuries of foreign rule, instituted reforms and rebuilt the Sumerian infrastructure, and helped usher in the final era of Sumerian rule in Mesopotamia under the Neo-Sumerian Empire.
Henry Freeman, Sumerians: A History From Beginning to End
Paul Kriwazczek, Babylon – Mesopotamia and the Birth of Civilization
Samuel Noah Kramer, “The Death of Ur-Nammu and His Descent to the Netherworld,” Journal of Cuneiform Studies
C. J. Gadd, The Cambridge Ancient History, CHAPTER XXII - BABYLONIA, c. 2120–1800 B.C.