RT Journal Article SR Electronic T1 Butting out in Canada: five down, eight to go JF Canadian Medical Association Journal JO CMAJ FD Canadian Medical Association SP 558 OP 558 DO 10.1503/cmaj.1041400 VO 171 IS 6 A1 Mackay, Bradford YR 2004 UL http://www.cmaj.ca/content/171/6/558.abstract