003780000a22001450004500060000800000082001200008100002200020100001900042245004000061250000600101260003100107260000900138300000900147650007600156  a100  a633 MAR  aLeonard, Warren H  aMartin, John H  aPrinciples of field crop production  a2  aNewyork, The macmillan co.  c1967  a1044  aField crop production/legumes/ crop improvement/field crops- harvesting