7Allan J A. Fortunately there are substitutes for water otherwise our hydropolitical futures would be impossible~ C ]//Priorities for water resources allocation and management. London: ODA, 1993:13-26.
8Allan J A. Overall perspectives on countries and regions[ C]// Water in the Arab world: perspectives and prognoses. Cam- bridge, Massachusetts: Harvard University Press, 1994:65 - 100.
9Hoekstra A Y. Virtual water trade : an introduction I C ]//Virtual water trade. Delft, the Netherlands: IHE, 2003:13 -23.
10Chapagain A K, Hoekstra A Y. Virtual water trade : a quantifica- tion of virtual water flows between nations in relation to crop trade~ C ~//Virtual water trade : proceedings of the international expert meeting on virtual water trade. Delft, the Netherlands: IHE, 2003:1 -118.