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\bibitem{Worobiec_etal2011} {\textquotedblleft}\textit{Air particulate emissions in developing countries : a case study in South Africa}{\textquotedblright}. Worobiec A, Potgieter-Vermaak SS, Berghmans P, Winkler H, Burger R, Van Grieken R, Analytical letters \textbf{44}, 1907 (2011).   http://doi.org/10.1080/00032719.2010.539734

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