Soil Map of the United States, Section 3. Atlas of American Agriculture.
Soil Map of the United States by Curtis F. Marbut and Associates in the Soil Survery, U.S. Department of Agriculture, F.J. Marschner, Cartographer and Associate in Compilation. 1931. Soils, Plate 5, Section 3. Lith. A. Hoen & Co., Inc. Atlas of American Agriculture.