2Simpson CR, Sheikh A. Trends in the epidemiology of asthma in England..A national study of 333 294 patients[J]. J R Soc Med, 2010,103(3):98-106.
3Anandan C,Nurmatov U, van Sehayek OC,et al. Is the prevalence of asthma declining? Systematic review of epidemiological studies [J]. Allergy,2010,65(2):152-167.
