1. Amaral, A. F. S., Arruda, M., Cabral, S., & Rodrigues, A. S. (2008). Essential and non-essential trace metals in scalp hair of men chronically exposed to volcanogenic metals in the Azores, Portugal. Environment International, 34, 1104–1108.
2. Arkimaa, H., Hyvönen, E., Lerssi, J., Loukola-Ruskeeniemi, K., Vanne, J. (1999). Compilation of maps of black shales in Finland: applications for exploration and environmental studies. In: Autio, S. (Ed.) Geological Survey of Finland. Special Paper. Current Research 1997–1998. Vol. 27, pp. 111–114. https://tupa.gtk.fi/julkaisu/specialpaper/sp_027.pdf
3. Arkimaa, H., Hyvönen, E., Lerssi, J., Loukola-Ruskeeniemi, K., Vanne, J. (2000). Proterozoic Black Shale Formations and Aeromagnetic Anomalies in Finland. 1: 1 000 000. (Map and database) Geological Survey of Finland, Espoo, Finland.
4. ATSDR. Agency for Toxic Substances and Disease Registry. (2008). Toxicological Profile for Cadmium (Draft for Public Comment). Atlanta, GA: U.S. Department of Health and Human Services, Public Health Service. Page last reviewed: March 12, 2015.
5. ATSDR Agency for Toxic Substances and Disease Registry. (2005a). Toxicological profile for Nickel. Atlanta, GA: U.S. Department of Health and Human Services, Public Health Service. https://wwwn.cdc.gov/TSP/ToxProfiles/ToxProfiles.aspx?id=245&tid=44