RT Journal Article SR Electronic T1 Varenicline can help smokers to stop smoking by gradual reduction JF Evidence Based Medicine JO Evid Based Med FD BMJ Publishing Group Ltd SP 133 OP 133 DO 10.1136/ebmed-2015-110199 VO 20 IS 4 A1 Karl Fagerstrom YR 2015 UL http://ebm.bmj.com/content/20/4/133.1.abstract AB