http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
Difference between the potentiometric surfaces of the Aquia Aquifer of ... and ... in southern Maryland
U.S. Department of the Interior, U.S. Geological Survey ; prepared in cooperation with Maryland Geological Survey and Maryland Tidewater Administration.
"Base from USGS Digital line graph, 250,000."
Coordinates for map based on: Sept. 1990.
Microfiche. <Sept. 1990-> [Denver, Colo. : U.S. Geological Survey]. microfiches : negative.