00411nam a2200133Ia 4500008004100000082003900041100001900080245006700099260004100166300001000207600001900217600001900236650002200255140113s9999    xx            000 0 und d  a"631.461.5(213)""1975""(082.2) L7"  a" Ayanaba, A."  aBiological nitrogen fixation in farming systems of the tropics  b"New York : John Wiley & sons, 1977"  a377p.  a" Dart, P. J."  a" Dart, P. J."  aNitrogen fixation