[1] Legacy, Schroeder Inst Tobacco Res & Policy Studies, Washington, DC USA
[2] Johns Hopkins Bloomberg Sch Publ Hlth, Dept Hlth Behav & Soc, Baltimore, MD USA
[3] Georgetown Univ, Med Ctr, Lombardi Comprehens Canc Ctr, Dept Oncol,Canc Prevent & Control Program, Washington, DC 20007 USA
[4] Univ N Carolina, Dept Hlth Behav, Gillings Sch Publ Hlth, Chapel Hill, NC USA