Prevalence of chronic obstructive pulmonary disease in China: a large, population-based survey.
Zhong N, Wang C, Yao W, Chen P, Kang J, Huang S, Chen B, Wang C, Ni D, Zhou Y, et al. Am J Respir Crit Care Med. 2007 Oct 15; 176(8):753-60. Epub 2007 Jun 15.