Yousif Ahmed, Amel, Mohammed A.H. Eltayeb, Abdul Khalik Wood, Moh. Suhaimi Hamza, and Md. Pauzi Abdulah. 2011. “Chemical Partitioning and Speciation of Some Trace Elements in Soil and Street Dust”. Asian Journal of Chemistry 24 (1):23-28. https://asianpubs.org/index.php/ajchem/article/view/15970.