1. U.S. Green Building Council (USGBC)http://www.usgbc.org/
2. Skyscraper Green Retrofits Guide, 2011http://www.geni.org/globalenergy/research/skyscraper-green-retrofitsguide/Skyscraper-Green-Retrofits-Guide-FINAL.pdf
3. Retrofitting State Owned Buildings;Heller,2011