1. Agency for Toxic Substances and Disease Registry. 2001a. ToxFAQs for sulfur dioxide [cited 2003 Sep 12]. Atlanta: US Department of Health and Human Services. Available from: URL: http://www.atsdr.cdc.gov/tfacts116.html.
2. Agency for Toxic Substances and Disease Registry. 2001b. ToxFAQs for sulfur trioxide and sulfuric acid [cited 2003 Sep 12]. Atlanta: US Department of Health and Human Services. Available from: URL: http://www.atsdr.cdc.gov/tfacts117.html.
3. Agency for Toxic Substances and Disease Registry. 2002. Hazardous substances emergency events surveillance 1999-2001 biennial report [cited 2003 Sep 12]. Atlanta: US Department of Health and Human Services. Available from: URL: http://www.atsdr.cdc.gov/HS/HSEES/.
4. American Chemical Society. 2002. Facts and figures for the chemical industry. Chemical and Engineering News [serial on line] 2002 June 24 [cited 2003 Sep 12]; Available from: URL: http://pubs.acs.org/cen/index.html.
5. Hazardous Substances Emergency Events in the Agriculture Industry and Related Services in Four Mid-Western States