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THUN, M., & HENLEY, S.(2006-10-12). Tobacco. In Cancer Epidemiology and Prevention. : Oxford University Press. Retrieved 19 May. 2013, from http://www.oxfordscholarship.com/view/10.1093/acprof:oso/9780195149616.001.0001/acprof-9780195149616-chapter-13.
THUN, MICHAEL J., and S. JANE HENLEY. "Tobacco." In Cancer Epidemiology and Prevention. : Oxford University Press, 2006-10-12. http://www.oxfordscholarship.com/view/10.1093/acprof:oso/9780195149616.001.0001/acprof-9780195149616-chapter-13.
THUN MJ, HENLEY SJ. Tobacco. In: Schottenfeld D, Fraumeni JF. Cancer Epidemiology and Prevention. Oxford University Press; 2006. http://www.oxfordscholarship.com/view/10.1093/acprof:oso/9780195149616.001.0001/acprof-9780195149616-chapter-13. Accessed May 19, 2013.