00336nam a2200097Ia 450000500170000010000210001724500310003826000090006952001410007858300190021920260716043351.0  aHELPMAN, Elnanan  aStructure of foreign trade  c1999  aDescribes what is known about foreign trade and in what waus ou understanding has improved as a result of the last 20 years of research.  c3/7/00kM2LMGR