State
Texas Division of Emergency Management
Texas Department of Health 
Office of the Governor
Homeland Security Task Force
Texas Engineering Extension Service (TEEX)

Federal
FBI
INS
FirstGov 
Centers for Disease Control and Prevention
United States Postal Service
FEMA
EPA-Chemical Emergency Preparedness and Prevention office
EPA- Environmental Response Center
The Office of Homeland Security
Critical Infrastructure Assurance Office
Weapons of Mass Destruction Civil Support Teams (Army National Guard)
TOXNET, Toxicology Data Network, National Library of Medicine
CHRIS Manual (Chemical Hazards Response Information System), US Coast Guard
Emergency Response Guidebook

Other
American Red Cross
National Terrorism Preparedness Institute
International Association of Emergency Managers
World Health Organization (WHO)
The Johns Hopkins University Center for Civilian Biodefense Studies
Terrorismanswers   Q & A