RT Journal Article SR Electronic T1 Trends in cigarette smoking cessation in the United States JF Tobacco Control JO Tob Control FD BMJ Publishing Group Ltd SP S3 OP S10 DO 10.1136/tc.2.suppl1.S4 VO 2 IS Suppl 1 A1 Gary A Giovino A1 Dana M Shelton A1 Michael W Schooley YR 1993 UL http://tobaccocontrol.bmj.com/content/2/Suppl_1/S3.2.abstract AB