1. Centers for Disease Control and Prevention Current cigarette smoking among adults, United States 2011 www.cdc.gov/mmwr/preview/mmwrhtml/mm6144a2.htm
2. Centers for Disease Control and Prevention Smoking-attributable mortality, years of potential life lost, and productivity lost, United States 2000-04 www.cdc.cdc.gov/mmwr/preview/mmwrhtml/mm5745a3.htm
3. Tobacco and oral diseases, 1999;EU Working Group on Tobacco and Oral Health;J Ir Dent Assoc,2000
4. World Health Organization Risks to oral health and intervention www.who.int/oral_health/action/risks/en/index2.html