Rosdahl, Caroline; Kowalski, Mary (2008). Textbook of Basic Nursing (ed. 9th). Lippincott Williams & Wilkins. m/s. 189. Dicapai pada 28 January 2015.
wikipedia.org
en.wikipedia.org
Angevine, J.; Cotman, C. (1981). Principles of Neuroanatomy. NY: Oxford University Press. |access-date= requires |url= (bantuan)|access-date= memerlukan |url= (bantuan)