"August 1980 4R-37518. August 1980 Base 4R-37509." At head of title: Appendix G. "Base compiled from U.S.G.S. quadrangle sheets and Plum Bayou Watershed." "Source: Data compiled by Watershed Planning Staff." "20,000 foot grid ticks based on Arkansas Coordinate System, South Zone." Includes location map. Available also through the Library of Congress Web site as a raster image.
United States. Soil Conservation Service
1980
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