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\bibitem{Johansson_etal1976} {\textquotedblleft}\textit{Elemental abundance variation with particle-size in north florida aerosols}{\textquotedblright}. Johansson TB, Van Grieken RE, Winchester JW, Journal of geophysical research \textbf{81}, 1039 (1976).   http://doi.org/10.1029/JC081I006P01039

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