http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
Classification of Medicago sativa L. using legume characters and flower colors
by Charles R. Gunn, W. H. Skrdla, and H.C. Spencer ; prepared by Agricultural Research Service.
Technical bulletin (United States. Department of Agriculture) ; no. 1574