1. Gray's Anatomy
2. Williams PL, ed. Gray's Anatomy, 38th Ed. New York: Churchill Livingstone, 1995, p 1470.
3. O'Rahilly R. Gardner-Gray-O'Rahilly Anatomy, 5th Ed. Philadelphia: WB Saunders Co, 1986, p 260.
4. Rosse C, Caddum-Rosse P. Hollinshead's Textbook of Anatomy, 5th Ed. Philadelphia: Lippincott-Raven, 1997, p 424.