The Product Space and its Consequences for Economic Growth. Ricardo Hausmann, March 5, 2007, Paper. “In this paper, we test the assumption underlying the foundational models of trade that there always exist products through which countries can express their endowments and technology. We map the `space’ of products in the world, and find it to be quite heterogeneous, with a central core and outer periphery. Moreover, we show that the way countries develop comparative advantage is far from random, and that the empirical rules observed herein predict, together with the structure of the product space, explain…” Link