00263nam a2200097Ia 4500008004100000082001500041100002100056245004000077260004100117300000700158140113s9999    xx            000 0 und d  a633.1   K7  a"Rohweder, D.A."  aMaximum crop yields : The challenge  a1967bAmerican Soc. AgronomycU.S.A.  a92