About: http://webisa.webdatacommons.org/61511532

Property	Value
http://www.w3.org/1999/02/22-rdf-syntax-ns#type	http://www.w3.org/ns/prov#Entity
http://www.w3.org/ns/prov#value	They are often vitiated by difficulties which lie rather below the surface, and are especially troublesome in attempts to express the equilibrium conditions of trade by mathematical formul??.
http://www.w3.org/ns/prov#wasQuotedFrom	econlib.org