Hervás, G., P. Frutos, A. R. Mantecón, and F. J. Giráldez. 2004. “Effect of the Administration of Quebracho Extract on Rumen Fermentation and Diet Digestibility in Sheep”. Spanish Journal of Agricultural Research 2 (1), 63-71. https://doi.org/10.5424/sjar/2004021-61.