Description
Item Description:Title from title screen (viewed on Sept. 4, 2008).
"February 1987."
Electronic resource.
Physical Description:vi, 27 pages : illustrations, 1 form ; 28 cm.
Format:Mode of access: Internet from USGS web site. Address as of 9/4/08: http://www.nwrc.usgs.gov/wdb/pub/hsi/hsi-133.pdf ; current access available via PURL.
Bibliography:Includes bibliographical references (pages 19-27).