7Sackett DL,Clarke M,Oxman AD,et al. Cochrane reviewers,hand- book 4.2, In renew manager [ M ]. Versions 4.2.0x ford, England : The cochrane collaboration,2002 : 13-36.
8Jadad AR, Moore A, Carroll D, et al. Assessing the quality of reports of randomized clinical trials is blinding necessary [J]. Control Clin Trials, 1996,17(1): 1-12.
9Tonelli MR. The limits of evidence based medicine [J]. Respir Care, 2001,46(12) : 1435-1440.