Helpman, Elhanan2019-10-111999Helpman, Elhanan. 1999. “The Structure of Foreign Trade.” Journal of Economic Perspectives13 (2): 121–44. https://doi.org/10.1257/jep.13.2.121.0895-33091944-7965http://nrs.harvard.edu/urn-3:HUL.InstRepos:41534613en-USThe Structure of Foreign TradeJournal Article2019-10-1110.1257/jep.13.2.121