http://www.zadig.it/news2001/amb/new-1101-1.htm
http://www.ilmac.net/macopinioni/torri_gemelle.htm
http://www.archimagazine.com/agemell.htm
http://www.twintowersday.com/index.old.html
http://www.kater.it/inchiestausa.htm
http://www.wallstreetitalia.com/articolo.asp?ART_ID=56676
http://members.fortunecity.com/goya8/index.html