Books
Dixit, Avinash and Norman, Victor D.: Theory of International Trade: A Dual, General Equlibrium Approach, 1980. Cambridge Economic Handbooks, Cambridge University Press. ch. 1, 2, 3, 4, and 9.
Feenstra, Robert C.: Advanced International trade: Theory and Evidence, 2004. Princeton University Press.
Krugman, Paul Rr: Rethinking international trade, 1994. MIT Press. ch. 5, 6.
Krugman, Paul R. : Geography and trade, 1991. MIT Press. all chapters.
Articles
Dornbusch, R., Fischer S., and Samuelson P.: "Comparative Advantage, Trade and Payments in a Ricardian Model with a Continuum of Goods " in American Economic Review . 67, 1977. pp. 823-839.
Freeman, Richard B.: "Trade Wars: The Exaggerated Impact of Trade in Economic Debate" in 2003. NBER Working Paper 10000. here.
Krugman, P.: "Scale Economies, Product Differentiation, and the Pattern of Trade" in American Economic Review 70, 1980. pp 950-959. here.
Krugman, P. R. and A. J. Venables: "Globalization and the inequality of nations" in Quarterly Journal of Economics 110, 1995. pp. 857-880. here.
Ottaviano, G. I. P. and D. Puga : "Agglomeration in the global economy: a survey of the “new economic geography”" in World Economy 25, 1998. pp. 707-731. here.