RT Journal Article SR Electronic T1 Canada: demolishing the power walls JF Tobacco Control JO Tob Control FD BMJ Publishing Group Ltd SP 7 OP 8 DO 10.1136/tc.12.1.7-a VO 12 IS 1 A1 Lynn Greaves YR 2003 UL http://tobaccocontrol.bmj.com/content/12/1/7.2.abstract AB