Lopes, M. M., A. A. C. Salviano, A. S. F. Araujo, L. A. P. L. Nunes, and M. E. Oliveira. “Changes in Soil Microbial Biomass and Activity in Different Brazilian Pastures”. Spanish Journal of Agricultural Research, Vol. 8, no. 4, 1, pp. 1253-9, doi:10.5424/sjar/2010084-1411.