TY  - BOOK
AU  - " Ayanaba, A."
TI  - Biological nitrogen fixation in farming systems of the tropics
U1  - "631.461.5(213)""1975""(082.2) L7" 
PB  - "New York : John Wiley & sons, 1977"
KW  - " Dart, P. J."
KW  - Nitrogen fixation
ER  -