a range of economies, including the United States, Japan, Republic of Korea and China. This discovery, and the first usage of the term "Kuznets Curve for Steel" and "Metal intensity Kuznets Curve" were by Huw McKay in a 2008 working paper (McKay 2008). This was subsequently developed in McKay (2012). A body of work on "Material Kuznets Curves" focused on non-ferrous metals has also emerged as academic and policy interest in resource intensity increased during the first two decades of the 21st century. References Bibliography Brenner, Y.S., Hartmut Kaelble, and Mark Thomas (1991): Income Distribution in Historical Perspective. Cambridge University Press. McKay, Huw (2008) ‘Metal intensity in comparative historical perspective: China, North Asia, the United States and the Kuznets curve’, Global Dynamic Systems Centre working papers, no. 6, September. McKay, Huw (2012) ‘Metal intensity in comparative historical perspective: China, North Asia, the United States ’, chapter 2 in Ligang Song and Haimin Lu (eds) The Chinese Steel Industry’s Transformation: Structural Change, Performance and Demand on Resources, Edward Elgar: Cheltenham UK. Economic inequality Economics curves