
CDC
http://www.cdc.gov/tobacco/data_statistics/fact_sheets/smokeless/smokeless_facts/index.htm
Mayo Clinic
http://www.mayoclinic.com/health/chewing-tobacco/CA00019
American Cancer Society
http://www.cancer.org/docroot/PED/content/PED_10_13X_Quitting_Smokeless_Tobacco.asp
http://www.cancer.org/docroot/PED/content/PED_10_13X_Quitting_Smokeless_Tobacco.asp
American Otolaryngology Head and Neck Surgery
http://www.entlink.org/HealthInformation/Smokeless-Tobacco.cfm
NIDA
http://www.drugabuse.gov/chat/chatfaqs308.html
