Brenes, A., A. Viveros, I. Goñi, C. Centeno, F. Saura-Calixto, and I. Arija. 2010. “Effect of Grape Seed Extract on Growth Performance, Protein and Polyphenol Digestibilities, and Antioxidant Activity in Chickens”. Spanish Journal of Agricultural Research 8 (2), 326-35. https://doi.org/10.5424/sjar/2010082-1199.