00295nam a2200109Ia 450000500170000000800410001708200160005810000190007424500400009326000440013330000080017720260224040958.0260224s9999||||xx |||||||||||||| ||und||  a633.099 PRA  aPratley, J.E.  0aPrinciples of field crop production  aNew York: Oxford University Pressc2003  a550