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\bibitem{Ro_etal2001} {\textquotedblleft}\textit{Heterogeneity assessment in individual CaCO$_{3}$-CaSO$_{4}$ particles using ultrathin window electron probe X-ray microanalysis}{\textquotedblright}. Ro C-U, Oh K-Y, Os{\'a}n J, de Hoog J, Worobiec A, Van Grieken R, Analytical chemistry \textbf{73}, 4574 (2001).   http://doi.org/10.1021/AC010438X

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