1. The National Commission on Terrorist Attacks Upon the United States The 9/11 commission report. Final report of the National Commission on Terrorist Attacks Upon the United States
2. Department of Homeland Security (DHS) Homeland Security Act of 2002, PUBLIC LAW 107-296. Report No. PUBLIC LAW 107-296
3. U.S. Government Accountability Office (GAO) 2008 1 17