00402nam a22001457a 4500020001800000082001900018100002100037245007500058260003100133300001900164650001700183650002200200650001400222700002000236  a9780262081822  a382.3  bHEL/T  aHelpman, Elhanan  aTrade policy and market structure/cElhanan Helpman and Paul R Krugman  aLondon:bMIT press,c1989.  a191p. ;b18cm.  aTrade Policy  aCommercial Policy  aMarketing  aKrugman, Paul R