Hernandez, F., M. D. Megias, J. Orengo, S. Martinez, M. J. Lopez, and J. Madrid. “Effect of Dietary Protein Level on Retention of Nutrients, Growth Performance, Litter Composition and NH3 Emission Using a Multi-Phase Feeding Programme in Broilers”. Spanish Journal of Agricultural Research, Vol. 11, no. 3, Jan. 2013, pp. 736-4, doi:10.5424/sjar/2013113-3597.