1. Detailed data table 6.9B–Types of illicit drug use in the past month among persons aged 18 to 25, by past month cigarettes use: Percentages, 2008 and 2009;Administration, S.A.a.M.H.S,2009
2. Table 31 selected drug use, past year alcohol use disorder, and past year mental health measures in Georgia, by age group: Estimated numbers (in thousands), annual averages based on 2014–2015 NSDUHs;Administration, S.A.a.M.H.S,2015
3. Current cigarette smoking among adults—United States, 2005–2012;Agaku;MMWR: Morbidity and Mortality Weekly Report,2014
4. National estimates of marijuana use and related indicators—National survey on drug use and health, United States, 2002–2014;Azofeifa;MMWR Surveillance Summaries,2016
5. Testing gateway theory: Do cigarette prices affect illicit drug use?;Beenstock;Journal of Health Economics,2002