1. Alley WM, Reilly TE, Franke OL (1999) Sustainability of ground-water resources. US Geol Surv Circ 1186. http://pubs.usgs.gov/circ/circ1186/ . Cited 8 Nov 2009
2. American Geological Institute (2008) Federal research funding of geosciences. Geoscience Currents 14. American Geological Institute, Alexandria, VA. http://www.agiweb.org/workforce/Currents-014-GeoscienceFederalResearchFunding.pdf . Cited 8 Nov 2009
3. Bredehoeft JD (2005) The conceptualization model problem: surprise. Hydrogeol J 13:37–46
4. Clark WC, Crutzen PJ, Schellnhuber HJ et al (2005) Science for global sustainability: toward a new paradigm. In: Schellnhuber HJ, Crutzen PJ, Clark WC (eds) Earth system analysis for sustainability, Chpt. 1. MIT Press, Cambridge, MA
5. de Marsily Gh, Delay F, Gonçalvès J et al (2005) Dealing with spatial heterogeneity. Hydrogeol J 13:161–183