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\bibitem{Nijsten_etal2018} Nijsten, G. - J., Christelis, G., Villholth, K. G., Braune, E., \& Gaye, C. B. (2018). Transboundary aquifers of Africa: Review of the current state of knowledge and progress towards sustainable development and management. \textit{Journal of Hydrology: Regional Studies}, \textit{20}, 21--34.

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