1. Agency for Toxic Substances and Disease Registry (ATSDR). (2005). Toxicological profile for lead. Washington, D.C.: United States Department of Health and Human Services.
2. ATSDR. (1988). The nature and extent of lead poisoning in children in the United States: A report to congress. Washington, D.C. United States Department of Health and Human Services.
3. Akhter, M. S., & Madany, I. (1993). Heavy metals in street and house dust in Bahrain. Water, Air and Soil Pollution, 66, 111–119.
4. Barnes, R. M. (1990). Childhood soil ingestion: How much dirt do kids eat? Analytical Chemistry, 62, 1023A–1033A.
5. Burt, J. E., & Barber, G. M. (1996). Elementary statistics for geographers (2nd ed., pp. 248–252). New York: The Guilford Press.