Kadthur, Jayachandra C., et al. “Prognostic Value of Ki 67 Proliferation Antigen in Canine Malignant Mammary Gland Tumours”. Brazilian Journal of Veterinary Pathology, vol. 4, no. 1, Mar. 2011, pp. 36-40, https://bjvp.org.br/bjvp/article/view/74.