1. Adams F. The genuine works of hippocrates. XL1. On superfoetation. New York: William Wood and Co; 1844. p. 94.
2. Pare A. The works of the famous Chirurgion Ambrose Parey, Book 25 Translated by Thomas Johnson. London: Thomas Cote and R Young; 1634. p. 979.
3. Ballantyne JW. Teratogenesis. An inquiry into the causes of Monstrosities. Edinburgh: Oliver and Boyd; 1897. p. 15.
4. Medusa. Wikipedia. The free encyclopedia. Google Scholar.
http:www.history.com/topics/ancienthistory/greek-mythology/videos/story-of-medusa
.
5. Assimakopoulos E, Athanasiadis A, Zafrakas M, Dragoumis K, Bontis J. Caudal regresion syndrome and sirenomelia in only one twin in two diabetic pregnancies. Clin Exp Obstet Gynecol. 2004;31(2):151–3.