, and Expertise: Causation and Precision in Upland Cotton', World Trade Review, 7 (1), 183-209 -- Gene M. Grossman and …Recommended readings (Machine generated): Bagwell, K. and R.W. Staiger (1999), 'An Economic Theory of GATT', American … the Theory of Optimum Subsidy', Journal of Political Economy, 71 (1), February, 44-50 -- Harry G. Johnson (1965), 'Optimal …