1. New world encyclopedia contributors, Surgery [internet]. New World encyclopedia 2008 Aug29,15:46UTC[cited2009Dec8].Available from http://www.newworldencyclopedia.org/entry/Surgery?oldid= 795211
2. Malcolm R. Calmer. Mooney’s surgery for Nurses. 16th ed. London: Churchill Livingstone, 2002:1 – 25
3. Suzanne C. Smeltzer, Brenda G. Bare. Text book of Medical surgical Nursing.10th ed. Philadelphia: Lippincott Williams and Wilkins, 2004: 409 –14
4. American society of Peri Anesthesia Nurse Website
5. Priseilla. K Gazarian. Identifying risk factors for postoperative. AORN Journa. 2006 October.