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\bibitem{Otten_etal1987} {\textquotedblleft}\textit{Study of inorganic ammonium compounds in individual marine aerosol particles by laser microprobe mass spectrometry}{\textquotedblright}. Otten P, Bruynseels F, Van Grieken R, Analytica chimica acta \textbf{195}, 117 (1987).   http://doi.org/10.1016/S0003-2670(00)85654-8

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