Bonnet, X., S. Akoka, R. Shine, and L. Pourcelot. “Disappearance of Eggs During Gestation in a Viviparous Snake (<i>Vipera aspis</I>) Detected Using Non-Invasive Techniques”. Acta Herpetologica, vol. 3, no. 2, Dec. 2008, pp. 129-37, doi:10.13128/Acta_Herpetol-2679.