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\bibitem{Xhoffer_etal1989} {\textquotedblleft}\textit{Application of electron energy loss spectroscopy to aerosols}{\textquotedblright}. Xhoffer C, Jacob W, Van Grieken R, Journal of aerosol science \textbf{20}, 1617 (1989).   http://doi.org/10.1016/0021-8502(89)90901-4

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