Mellor, John W. Issues in world agriculture : a U.S. perspective 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 LCCN: 3704 Subjects--Topical Terms: Agricultura--E.U.A.Agricultura--E.U.A.