00282nam a2200109Ia 450000500170000000800410001708200140005810000160007224500370008826000390012530000080016420260224040810.0260224s9999||||xx |||||||||||||| ||und||  a338.1 HEA  aHeady, E.O. 0aAgricultural production function  aIOWA: State University Pressc1961  a667