by Combs, R.P, Marion, B.W
Published in Working paper, N.C. Project 117 - North Central Agricultural Experiment Stations (USA) (01.04.1984)

by Cook, H.L, Combs, R.P
Published in Cooperative research report - United States Dept. of Agriculture, Economics, Statistics, and Cooperatives Service (USA) (01.07.1982)

by Combs, R.P, Pulver, G.C, Shaffer, R.E
Published in Publication - Cooperative Extension Programs. University of Wisconsin - Extension (1983)