Description
Item Description:Title from PDF title screen (viewed May 19, 2004).
Electronic resource.
Physical Description:vi, 19 pages : digital, PDF file.
Format:Mode of access: Internet from the USGS web site. Address as of 1/7/08: http://pubs.usgs.gov/of/2004/1203/pdf/ofr20041203.pdf ; current access via PURL.
System requirements: Adobe Acrobat Reader.
Bibliography:Includes bibliographical references (pages 18-19).