by Frey, H.T
Published in Agricultural economic report - United States Dept. of Agriculture (USA) (01.08.1982)

by Frey H.T
Published in Farmline (1982)

by Frey, H.T
Published in Agricultural economic report - United States Dept. of Agriculture, Economics, Statistics, and Cooperatives Service (USA) (01.11.1979)

by Frey H.T, Hexem R.W
Published in Agricultural economic report - United States Dept. of Agriculture (USA). no. 535 (1985)

by Frey, H.T, Schaller, W.N, Anderson, W.D
Published in Farmline (01.05.1984)

by Durost, D.D, Black, E.T. (comp.), Wilkins, S.R, Evans, R.B, Kirkley, J.E, Frey, H.T, Paul, D.A, Harrington, D.N
Published in Stat Bull US Dep Agric (1976)