1. Molecular Biology of the Cell;Alberts,2002
2. Practical Animal Morphology;Al-Hussaini,1967
3. Embryology and Phylogeny in Annelids and Arthropods;Anderson,1973
4. Aparicio, M.T., 1937. Certain reproductive organs in the Neritidae. Malacologia 61, 525–549.
5. Aristotle, 1910. The Works of Aristotle. Translated into English under the editorship of J.A. Smith and W.D. Ross. vol. IV. Historia Animalium, by D’Arcy Wentworth Thompson. Clarendon Press, Oxford.