Source

"Smoking and Mortality — Beyond Established Causes." NEJM. Brian D. Carter, M.P.H., Christian C. Abnet, Ph.D., Diane Feskanich, Sc.D., Neal D. Freedman, Ph.D., Patricia Hartge, Sc.D., Cora E. Lewis, M.D., Judith K. Ockene, Ph.D., Ross L. Prentice, Ph.D., Frank E. Speizer, M.D., Michael J. Thun, M.D., and Eric J. Jacobs, Ph.D., 12 Feb. 2015.

http://www.nejm.org/doi/pdf/10.1056/NEJMsa1407211