Ullstrup, A. J. (Arnold John), 1907-
Washington, D.C. : Agricultural Research Service, U.S. Dept. of Agriculture in cooperation with Purdue University Experiment Station, 1961.
1961
Wischmeier, Walter H., 1911-
Washington, D.C. : Agricultural Research Service, U.S. Dept of Agriculture in cooperation with Purdue Agricultural Experiment Station, 1965.
1965