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\bibitem{Leysen_etal1987} {\textquotedblleft}\textit{A study of the weathering of an historic building}{\textquotedblright}. Leysen L, Roekens E, Komy Z, Van Grieken R, Analytica chimica acta \textbf{195}, 247 (1987).   http://doi.org/10.1016/S0003-2670(00)85666-4

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