Schünemann Holger J, Woodhead Mark, Anzueto Antonio, Buist Sonia, Macnee William, Rabe Klaus F, Heffner John
CLARITY Research Group, Department of Epidemiology, Italian National Cancer Institute "Regina Elena", Rome, Italy.
Lancet. 2009 Feb 28;373(9665):774-9. doi: 10.1016/S0140-6736(08)61347-1. Epub 2008 Oct 3.