8Coultas DB, Mape ID, Gagnon R, et al. The health impact of un diagnosed airflow obstruction in a nationalsample of United States adults[J]. Am J Respir Crit Care Med,2001 (164) :372 -377.
9Michaud CM, Murray C J, Bloom BR. Burden of disease-implications for future research [ J ]. JAMA, 2001 ( 285 ) : 535 - 539.