Rodrigues, M. A., V. Gomes, L. G. Dias, J. Pires, C. Aguiar, and M. Arrobas. “Evaluation of Soil Nitrogen Availability by Growing Tufts of Nitrophilic Species in an Intensively Grazed Biodiverse Legume-Rich Pasture”. Spanish Journal of Agricultural Research, Vol. 8, no. 4, 1, pp. 1058-67, doi:10.5424/sjar/2010084-1399.