Centers for Disease Control and Prevention. Smoking and Tobacco Use: Smoking Cessation. http://www.cdc.gov/tobacco/data_statistics/fact_sheets/cessation/quitting/ 3/20/2011. Accessed June 8, 2011
American Cancer Society. Guide to Quitting Smoking. October 22, 2008.Accessed February 28, 2009 from http://www.cancer.org/docroot/PED/content/PED_10_13X_Guide_for_Quitting_Smoking.asp.