Description
Item Description:Title from PDF title screen (viewed on Feb. 21, 2008).
Electronic resource.
Physical Description:iii, 43 pages : digital, PDF file.
Format:Mode of access: Internet via the USGS web site. Address as of 02/22/08: http://pubs.usgs.gov/of/2008/1020/pdf/ofr20081020.pdf ; current access available via PURL.
Bibliography:Includes bibliographical references.