1. Centre for Evidence Based Medicine (CEBM). Oxford Centre for Evidence-based Medicine – levels of evidence (March 2009). http://www.cebm.net/index.aspx?o=1025 [cited 15.06.2010].
2. Análisis crítico de la literatura biomédica;Manterola;Rev Med Clin Condes,2009
3. Users’ guide to the surgical literature: how to use a systematic literature review and meta-analysis;Bhandari;Can J Surg,2004
4. CASPe. Critical appraisal skills programme español. Available at: http://www.redcaspe.org [cited 08.04.2011]
5. Improving the quality of reports of meta-analyses of randomised controlled trials: the QUOROM statement. QUOROM Group;Moher;Br J Surg,2000