Clauss, M.; Pellegrini, N.; Castell, J.C.; Kienzle, E.; Dierenfeld, E.S.; Hummel, J.; Flach, E.J.; Streich, W.J.; Hatt, J.M. 2006. Antioxidant status of faeces of captive black rhinoceros (Diceros bicornis) in relation to dietary tannin supplementation. Journal of Veterinary Medicine A 53: 319-322, figs. 1-2, table 1.