1. International Committee of Medical Journal Editors. Uniform requirements for manuscripts submitted to biomedical journals. IIIJ. Obligation to Register Clinical Trials. Available at: http://www.icmje.org/#clin_trials. Accessed November 19, 2008.
2. PRISMA: Transparent reporting of systematic reviews and meta-analyses. Available at: http://www.prisma-statement.org/index.htm. Undated. Accessed September 30, 2009.
3. Meta-analysis of observational studies in epidemiology: A proposal for reporting;Stroup;JAMA,2000
4. International Committee of Medical Journal Editors. Uniform requirements for manuscripts submitted. Available at: http://www.icmje.org/index.html#top. Accessed November 19, 2008.
5. American Medical Association Manual of Style;Iverson,1998