1. U. S. Dept. Agr. Tech. Bul.;Blaisdell,1953
2. Effects of soil conservation;Brown,1950
3. Rates of sediment production in midwestern United States;Gunnar,1948
4. Carnegie Inst. Washington Yearbook;Clements,1922
5. Conrad, V. A., , Methods in climatology, Harvard Univ. Press, 1946,