=== World Trade Centers kollaps ===
Tekniske undersøgelse af tvillingetårnenes og World Trade Center nr. 7's kollaps blev foretaget af det amerikanske handelsministerium [[National Institute of Standards and Technology]] (NIST). Målene for denne undersøgelse var at fastslå, hvorfor bygningerne kollapsede, omfanget af skader og dødsfald samt de procedurer, der er involveret i udformningen og forvaltningen af World Trade Center.<ref name="NISTInvest">{{cite web |title=NIST’s World Trade Center Investigation |url=http://www.nist.gov/public_affairs/factsheet/nist_investigation_911.htm |work=National Institute of Standards and Technology |publisher=U.S. Department of Commerce |date=14. december 2007 |access-date=3. maj 2008 |archive-date=25. december 2018 |archive-url=https://web.archive.org/web/20181225172357/https://www.nist.gov/public_affairs/factsheet/nist_investigation_911.htm%20 |url-status=dead }}</ref> Undersøgelsen af sammenbruddet i 1 WTC og 2 WTC blev tilendebragt i oktober 2005 og undersøgelsen af sammenbruddet i 7 WTC var færdig august 2008.<ref>{{cite web |url=http://wtc.nist.gov/reports_october05.htm |title=Final Reports of the Federal Building and Fire Investigation of the World Trade Center Disaster |date=8. juni 2006 |access-date=30. april 2008 |work=[[National Institute of Standards and Technology]] |publisher=[[United States Department of Commerce]]}}</ref><ref name="NISTTheory">{{cite web |url=http://www.nist.gov/public_affairs/releases/wtc082108.html |title=NIST WTC 7 Investigation Finds Building Fires Caused Collapse |date=21. august 2008 |access-date=22. august 2008 |work=[[National Institute of Standards and Technology]] |publisher=[[United States Department of Commerce]] |archive-date=25. december 2018 |archive-url=https://web.archive.org/web/20181225172011/https://www.nist.gov/public_affairs/releases/wtc082108.html%20 |url-status=dead }}</ref>
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