00244nam a2200097Ia 4500008004100000082002900041245004000070260001700110300000900127650001000136140113s9999    xx            000 0 und d  a631.416.1'4:581.001.5 K1  aNitrogen - 15 in soil plant studies  b"IAEA, 1971"  a255p  aSoils