Description
Item Description:Title from PDF title screen (viewed on Apr. 24, 2006).
Electronic resource.
Physical Description:vi, 42 pages : digital, PDF file.
Format:Mode of access: Internet from the USGS web site. Address as of 8/17/07: http://pubs.usgs.gov/of/2006/1058/pdf/ofr20061058.pdf; current access via PURL.
Bibliography:Includes bibliographical references (pages 39-42).