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Higgins, Julian P T; Altman, Douglas G; Gøtzsche, Peter C; Jüni, Peter; Moher, David; Oxman, Andrew D; Savovic, Jelena; Schulz, Kenneth F; Weeks, Laura; Sterne, Jonathan A C; Cochrane Bias Methods, Group; Cochrane Statistical Methods, Group (2011). The Cochrane Collaboration's tool for assessing risk of bias in randomised trials. BMJ, 343, d5928. London: BMJ Publishing Group 10.1136/bmj.d5928