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\bibitem{Smoron+Kowalczyk2012} Smoro{\'n}, S., \& Kowalczyk, A. (2012). Nitrogen and Phosphorus dynamics in the surface flowing waters of the loessial areas in Northern Malopolska. \textit{Pol. J. Environ. Stud.}, \textit{21}(15a), 392--395.

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