1. Adriano, D. C. (2001). Trace elements in terrestrial environments: Biogeochemistry, bioavailability and risks of metals (2nd ed.). New York: Springer.
2. Akele, M. L., Kelderman, P., Koning, C. W., & Irvine, K. (2016). Trace metal distributions in the sediments of the Little Akaki River, Addis Ababa, Ethiopia. Environmental Monitoring and Assessment, 188(7), 389.
3. Awagu, E. F., & Uduma, A. U. (2014). Manganese as a reference element for the interpretation of Lead enrichment/depletion in selected farming soils in Nigeria. The international journal of engineering and science, 3(2), 79–86.
4. Awofolu, O., Mbolekwa, Z., Mtshemla, V., & Fatoki, O. (2005). Levels of trace metals in water and sediment from Tyume River and its effects on an irrigated farmland. Water S. A., 31(1), 87–94.
5. Barakat, A., El Baghdadi, M., Rais, J., & Nadem, S. (2012). Assessment of heavy metal in surface sediments of Day River at Beni-Mellal region, Morocco. Research Journal of Environmental and Earth Sciences, 4(8), 797–806.