1. Commentary on the utility of the ecological footprint concept;Ayres;Ecol Econ,2000
2. Brown MT, Bardi E. Handbook of emergy evaluation. A compendium of data for emergy computation issued in a series of folios. Folio #3: Emergy of ecosystems. Center for Environmental Policy, Environmental Engineering Sciences, University of Florida, Gainesville; 2001. Available at http://www.emergysystems.org/folios.php [accessed 02.06.09.
3. Emergy analysis and environmental accounting;Brown;Encycloped Energy,2004
4. Buenfil AA. Emergy evaluation of water. Dissertation presented to the graduate school of the University of Florida in partial fulfillment of the requirements for the degree of doctor of philosophy. University of Florida; 2001.
5. CAN – Comunidad Andina de Naciones. Bases de la Alianza Energética Andina – Antecedentes para su formulación; 2004. Available at http://intranet.comunidadandina.org/Documentos/DTrabajo/SGdt256_R1.doc.