I added it as the second-to-last in the list of links I put on my site yesterday.
That 2007 “Synthetic Terror” book chapter credits the silica coating point. (See Amazon)
But I find Al Qaeda’s attack plans more probative.
Plans for attack
Jonathan Spyer, “The Al-Qaida Network and Weapons of Mass Destruction,” Middle East Review of International Affairs (September 2004)
http://meria.idc.ac.il/journal/2004/issue3/jv8n3a3.html
Coded video found on Zawahiri’s computer said to show plans to weaponize anthrax
http://www.mintertainment.com/videos/video/How_Tic_Tacs_Came_To_Dominate_Planet
Leonard A. Cole, “Bioweapons, Proliferation, and the US Anthrax Attack:
Strategic Insights, Center for Contemporary Conflict”
http://www.ccc.nps.navy.mil/si/2007/Aug/coleAug07.pdf