http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
Distribution of selected herbicides and nitrate in the Mississippi River and its major tributaries, April through June 1991
1 online resource (v, 35 pages) : illustrations, map.
by D.A. Goolsby, R.C. Coupe, and D.J. Markovchick.
Includes bibliographical references (pages 34-35).
Water-resources investigations report ; 91-4163