M. I. YUSUF, A. L. NGALA, R. ABDULLAHI, A. K. HASSAN, and I. M. BELLO, “Influence of groundnut varieties and bradyrhizobium-phosphorus combination on soil nitrogen content in Maiduguri, Nigeria”, Agr. Foo. Nat. Res. J., vol. 5, no. 2, pp. 156–163, Sep. 2026, doi: 10.5281/zenodo.23436052.