: a U.S. perspective Mellor, John W. creator text monographic 51-30 Sobretirode : Hildreth, R. J., ed. Agriculture and rural areas approaching the twenty-first century; challenges for agricultural economies -- [s.l.]: Iowa State University, 1968. pp. 158-167 Agricultura E.U.A Agricultura E.U.A 3704 971013 20220329133230.0