Description
Item Description:Title from title screen (viewed on Mar. 4, 2008).
Physical Description:vi, 34 pages : digital, PDF file.
Format:Mode of access: Internet from the USGS web site. Address as of 03/04/08: http://pubs.usgs.gov/sir/2007/5185/pdf/sir20075185.pdf; current access available via PURL.
Bibliography:Includes bibliographical references (pages 28-29).