Martin Polo, J., C. Valle Gutierrez, A. Blanco de Pablos, and M. Sánchez Rodríguez. “Forages Resources in "dehesa" System: Fertilization, Tillage and Forage Sowing. I. Influence to the Environment (soil and Vegetation)”. Spanish Journal of Agricultural Research, Vol. 1, no. 1, Mar. 2003, pp. 23-33, doi:10.5424/sjar/2003011-6.