Mode of access: Internet from the USGS web site. Address as of 12/12/07: http://pubs.usgs.gov/fs/2007/3093/pdf/fs20073093.pdf; current access via PURL.
Note
Title from PDF title screen (viewed on Nov. 14, 2007).
"November 2007."
"U.S. Department of the Interior, U.S. Geological Survey."