Are They Natural?

"Regional Trading Arrangements: Natural or Super-Natural?" (with E. Stein and S.J. Wei), American Economic Review 86, no.2, May 1996, 52-56. NBER Working Paper No. 5431.

"Trading Blocs and the Americas: The Natural, the Unnatural, and the Super-Natural" (with E. Stein and S.J.Wei), full version, CIDER Working Paper No. C94-034. Abridged version, Journal of Development Economics 47, no. 1, June 1995, 61-95.