http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
Water quality in the Potomac River basin, Maryland, Pennsylvania, Virginia, West Virginia, and the District of Columbia, 1992-96
National Water-Quality Assessment Program (U.S.)
1 online resource (38 pages) : color illustrations, color maps.
Includes bibliographical references (pages 34-36).