1. British Geological Survey 1990. Long-term Hydrograph of groundwater levels in the chalk of southern England (wallchart) Wallingford: British Geological Survey.
2. British Geological Survey 1992. Long-term hydrograph of groundwater levels in the Dalton Holme estate well in the Chalk of Yorkshire (wallchart). Wallingford: British Geological Survey.
3. Burdon, D.J. 1982. Hydrogeological conditions in the Middle East. Quarterly Journal of Engineering Geology
15, 71–82.
4. Davis, S.N. and R.J.M. De Wiest 1966. Hydrogeology. New York: Wiley. (See especially Ch. 12.)
5. Doornkamp, J.C. and K.J. Gregory (eds) 1980. Atlas of drought in Britain 1975–76. London: Institute of British Geographers.