1. Grana R, Benowitz N, Glantz SA. Background paper on e-cigarettes (electronic nicotine delivery systems). University of California, San Francisco Center for Tobacco Control Research and Education. Published December 2013. Available at: 〈http://escholarship.org/uc/item/13p2b72n〉 Accessed 4 September 2017.
2. Schoenborn CA, Gindi RM Electronic cigarette use among adults: United States, 2014. NCHS Data Brief, Number 217. Published October 2015. Available at: 〈www.cdc.gov/nchs/data/databriefs/db217.pdf〉 Accessed 4 September 2017.
3. The emerging phenomenon of electronic cigarettes;Caponnetto;Expert Rev Respir Med,2012
4. Smoking revolution: a content analysis of electronic cigarette retail websites;Grana;Am J Prev Med,2014
5. Association between electronic cigarette use and changes in quit attempts, success of quit attempts, use of smoking cessation pharmacotherapy, and use of stop smoking services in England: time series analysis of population trends;Beard;BMJ,2016