1. Agency for Toxic Substances and Disease Registry (ATSDR) (1990) Toxicological profile for Copper U.S. Department of Health and Human Services, Public Health Service, Division of Toxicology 1600, Atlanta, GA 30333
2. Agency for Toxic Substances and Disease Registry (ATSDR) (2005) Toxicological profile for Nickel U.S. Department of Health and Human Services, Public Health Service, Division of Toxicology 1600, Atlanta, GA 30333
3. Agency for Toxic Substances and Disease Registry (ATSDR) (2007) U.S. Department of Health and Human Services, Public Health Service, Division of Toxicology 1600, Atlanta, GA 30333
4. Agency for Toxic Substances and Disease Registry (ATSDR) (2012) Toxicological profile for Chromium U.S. Department of Health and Human Services, Public Health Service, Division of Toxicology 1600, Atlanta, GA 30333
5. Ailsa A, Michael A (1999) A dictionary of Earth Science. Oxford University Press, London