6Balassa, Bela. Trade Liberalization and ' Revealed' Comparative Advantage. Manchester School of Economic and Societal Studies, 1965,33:99-123.
7Hausmann, Ricardo. , Hwang, Jason. , Rodrik, Dani. What You Export Matters. NBER Working Paper NO. 11905, December,2005.
8Lall, Sanjaya. , Weiss, John., Zhang, Jinkang. The 'Sophistication' of Exports: A New Measure of Product Characteristics. ADB Institute Discussion Paper NO. 23,2005.