1. Angelini, P., 1997, Correlation and spectral analysis of two hydrogeological systems in Central Italy. Hydrological Sciences Journal, 42, 425–439.
2. Beekman, H.E. and Xu, Y., 2003, Review of groundwater recharge estimation in arid and semi-arid Southern Africa. In: Xu, Y. and Beekman, H.E. (eds.), Groundwater Recharge Estimation in South Africa. UNESCO IHP Series No. 64, p. 3–18.
3. de Vries, J.J. and Simmers, I., 2002, Groundwater recharge: an overview of processes and challenges. Hydrogeology Journal, 10, 5–17.
4. Healy, R.W. and Cook, P.G., 2002, Using groundwater levels to estimate recharge. Hydrogeology Journal, 10, 91–109.
5. Kim, T.H., 2001, An Alternative Framework for Analyzing Hydraulic Information of the Groundwater Flow System. Ph.D. thesis, Seoul National University, Seoul, 177 p.