1. a Cancer Prevention Fellowship Program, Center for Cancer Training, Behavioral Research Program, Division of Cancer Control and Population Sciences, National Cancer Institute , Bethesda , Maryland , USA
2. b Tobacco Control Research Branch, Behavioral Research Program, Division of Cancer Control and Population Sciences, National Cancer Institute , Bethesda , Maryland , USA
3. c Harvard School of Public Health , Boston , Massachusetts
4. d Health Communication and Informatics Research Branch, SAIC, Inc., National Cancer Institute–Frederick , Frederick , Maryland , USA