Charles L. Redman, The Rise of Civilization—From Early Farmers to Urban Society in the Ancient Near East (San Francisco: W.H. Freeman, 1978), p. 268; Andrew Sherratt, “Plough and Pastoralism: Aspects of the Secondary Products Revolution,” in Patterns of the Past: Studies in Honour of David Clarke, ed. Ian Hodder, Glenn Isaac and Normand Hammond (Cambridge, UK Cambridge Univ. Press, 1981), pp. 261–305.