RT Journal Article SR Electronic T1 Reflections on the saga of tar content: why did we measure the wrong thing? JF Tobacco Control JO Tob Control FD BMJ Publishing Group Ltd SP 90 OP 94 DO 10.1136/tc.9.1.90 VO 9 IS 1 A1 Nigel Gray YR 2000 UL http://tobaccocontrol.bmj.com/content/9/1/90.abstract AB