RT Journal Article SR Electronic T1 Varenicline: quantifying the risk JF Canadian Medical Association Journal JO CMAJ FD Canadian Medical Association SP 1404 OP 1405 DO 10.1503/cmaj.111-2070 VO 183 IS 12 A1 Edward N. Squire YR 2011 UL http://www.cmaj.ca/content/183/12/1404.4.abstract