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\bibitem{Gysels+VanGrieken1999} {\textquotedblleft}\textit{Field evaluation of a wind tunnel-impactor system for sampling ambient aerosols}{\textquotedblright}. Gysels K, Van Grieken R, Journal of aerosol science \textbf{30}, 639 (1999).   http://doi.org/10.1016/S0021-8502(98)00747-2

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