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\bibitem{Eltayeb_etal1993} {\textquotedblleft}\textit{Aerosol-soil fractionation for Namib Desert samples}{\textquotedblright}. Eltayeb MAH, Van Grieken RE, Maenhaut W, Annegarn HAJ, Atmospheric environment: part A : general topics \textbf{27}, 669 (1993).   http://doi.org/10.1016/0960-1686(93)90185-2

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