1. Letters carried fresh anthrax;Baltimore Sun,2002
2. Massive cross-contamination feared;New York Daily News,2001
3. Lengel A. Little progress in FBI probe of anthrax attacks. Washington Post, http://www.washingtonpost.com/wp-dyn/content/article/2005/09/15/AR2005091502456_pf.html. Accessed 08.04.08.
4. President Bush signs Project Bioshield Act of 2004. www.whitehouse.gov. Accessed 07.04.08.
5. The powder: from Berlin to Brazil, the ‘anthrax’ letters;Erlanger;New York Times,2001