http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
Map showing the potentiometric surface of the Magothy aquifer in Southern Maryland, September 1982
by Frederick K. Mack, Judith C. Wheeler, and Stephen E. Curtin.
Relief shown by contours and spot heights.
"Prepared in cooperation with Maryland Geological Survey and Maryland Energy Administration."
Water-resources investigations report ; 83-4282