00367nam a2200121Ia 4500008004100000082003400041100002000075245005700095260004000152300001200192600001900204650002200223140224s9999    xx            000 0 und d  a581.138:631.46:661.5.001.4 M0  aBergersen, F.J.  aMethods for evaluating biological nitrogen fixation.  aChichesterbJohn Wiley & Sonsc1980  ax,700p.  aF.J. Bergersen  aNitrogen fixation