New Cumberland, Pa. : U.S. Dept. of the Interior, U.S. Geological Survey ; Denver, Colo. : U.S. Geological Survey, Branch of Information Services [distributor], 2003
Includes bibliographical references (pages 26-27).
Also available via Internet at the USGS web site. Address as of 02/28/04: http://pa.water.usgs.gov/reports/wrir03-4201.pdf; current access available via PURL.