000 00295nam a2200121Ia 4500
008 160906s9999 xx 000 0 und d
100 _aJohnson, Paul R
245 _aChanges in corn yields 1947 -1954
260 _aChicago
260 _bUniversity of Chicago
260 _c1958
300 _a7p.
999 _c105229
_d105229