00287nam a2200109Ia 450000500170000000800410001708200140005810000180007224500390009026000400012930000080016920260225044753.0260224s9999||||xx |||||||||||||| ||und||  a338.1 HEA  aEarl O. Heady 0aAgricultural production functions   aIOWA: State University Press c1961  a667