Portland, OR (333 S.W. First Ave., P.O. Box 3890, Portland 97208-3890) : U.S. Dept. of Agriculture, Forest Service, Pacific Northwest Research Station, [2001]
Also available via Internet from the Pacific Northwest Research Station web site. Address as of 7/11/02: http://www.fs.fed.us/pnw/pubs/rp539.pdf; current access is available via PURL.