N. Ayuni, O. Radziah, U. A. A. Naher, Q.A. Panhwar, and M. S. Halimi. "Effect of Nitrogen on Nitrogenase Activity of Diazotrophs and Total Bacterial Population in Rice Soil." Journal of Animal and Plant Sciences, vol. 25, no. 5, 2015, pp. 1358-1364.