References:

1. United States Department of Health & Human Services Substance Abuse and Mental Health Services Administration. Drug Abuse Warning Network, 2004: National Estimates of Drug-Related Emergency Department Visits.
   
2. Mokdad, Ali H., PhD, James S. Marks, MD, MPH, Donna F. Stroup, PhD, MSc, Julie L. Gerberding, MD, MPH, "Actual Causes of Death in the United States, 2000," Journal of the American Medical Association, March 10, 2004, Vol. 291, No. 10, pp. 1238-1245.
   
3. United States Department of Health & Human Services. Results from the 2004 National Survey on Drug Use and Health: National Findings.