Rodrigues, J., D. Soares, and J. Silva. “Sexing Freshwater Turtles: Penile Eversion in <em>Phrynops tuberosus</Em> (Testudines: Chelidae)”. Acta Herpetologica, vol. 9, no. 2, Nov. 2014, pp. 259-63, doi:10.13128/Acta_Herpetol-14736.