References
 1. Arc Hydro Groundwater: GIS for Hydrogeology 
David R. Maidment

http://esripress.esri.com/display/index.cfm?fuseaction=display&websiteID=192&moduleID=0

2. Arc hydro:GIS for water resources
 David R. Maidment

http://books.google.com/books/about/Arc_hydro.html?id=1WRvmYju-nkC