Zuffi, M. A. L., and A. Plaitano. “Similarities and Differences in Adult Tortoises: A Morphological Approach and Its Implication for Reproduction and Mobility Between Species”. Acta Herpetologica, vol. 2, no. 2, Nov. 2007, pp. 79-86, doi:10.13128/Acta_Herpetol-2220.