Description
Item Description:Title from PDF title screen (viewed on Nov. 14, 2008).
Electronic resource.
Physical Description:vi, 42 pages : digital, PDF file.
Format:Mode of access: Internet via the USGS web site. Address as of 11/19/08: http://pubs.usgs.gov/of/2008/1269/pdf/OF2008%5f1269.pdf ; current access available via PURL.
Bibliography:Includes bibliographical references.