00274nam a2200109Ia 4500008004100000082001700041100002300058245003500081260001700116300001000133650002100143140113s9999    xx            000 0 und d  a633.001.7 M4  a" Simmonds, N. W."  aPrinciples of crop improvement  b"ELBS, 1984"  a408p.  aCrop improvement