Description
Item Description:Title from title screen (viewed on Oct. 31, 2008).
Electronic resource.
Physical Description:14 pages : digital, PDF file.
Format:Mode of access: Internet from the NPS web site. Address as of 10/31/08: http://www.nps.gov/nr/publications/bulletins/nrb18/nrb18.pdf ; current access available via PURL.
Bibliography:Includes bibliographical references (pages 13-14).