107 pages : color illustrations, color map ; 28 cm
OCLC
ocm41289770
Cover title.
"April 1999."
Not distributed to depository libraries in a physical form.
"GAO/RCED-99-93."
"B-280294"--P. [1].
Includes bibliographical references.
Available via Internet from the GPO Access Web site. Address as of 4-25-01: http://frwebgate.access.gpo.gov/cgi-bin/getdoc.cgi?dbname=gao&docid=f:rc99093.pdf; current access is available via PURL.