1. Hospitals Participating in NSQIP. Available at: http://site.acsnsqip.org/participants/. Accessed April 2014.
2. UHC Database. Available at: www.uhc.edu. Accessed April 2014.
3. ICD9CM Coding System. Available at: http://www.cdc.gov/nchs/icd/icd9cm.htm. Accessed April 2014.
4. CPT Coding System. Available at: http://www.ama-assn.org/ama/pub/physician-resources/solutions-managing-your-practice/coding-billing-insurance/cpt.page. Accessed April 2014.