http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
the U.S. National Plant Germplasm System
United States National Plant Germplasm System
1 online resource (20 pages) : color illustrations, color map.
"Issued December 1960; revised April 1996"--Title page verso.
Program aid (United States. Department of Agriculture) ; no. 1470