1. Center for Disease Control (CDC). Tobacco Info-State & National Tobacco Control Highlights. 2003. Pennsylvania. Adult tobacco use in Pennsylvania. Current cigarette smoking among adults aged 18 and older, 1997. Http://www.cdc.gov/tobacco/statehi/htmltext/pa_sh.htm. [Accessed 4/15/03].
2. Cigarette smoking and occupational status: 1977 to 1990.
3. 2000. The prevalence of selected cigarette smoking behaviors by occupation in the United States: Work, smoking and health. A NIOSH Scientific Workshop.