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\bibitem{Claereboudt_etal1993} {\textquotedblleft}\textit{Laser microprobe mass spectrometry of quaternary phosphonium salts: direct versus matrix-assisted laser desorption}{\textquotedblright}. Claereboudt J, Claeys M, Geise H, Gijbels R, Vertes A, Journal of the American Society for Mass Spectrometry \textbf{4}, 798 (1993).   http://doi.org/10.1016/1044-0305(93)80038-Z

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