http://digfir-published.macmillanusa.com/krugmanapecon2e/krugmanapecon2e_sect8_1.htmlChapter Introduction56831ae0757a2e5f3d000003
http://digfir-published.macmillanusa.com/krugmanapecon2e/krugmanapecon2e_sect8_1_dlap.xmlDLAP questions56831ae0757a2e5f3d000003