AMSTAR 2: a critical appraisal tool for systematic reviews that include randomised or non-randomised studies of healthcare interventions, or both
B. Shea, Barnaby C Reeves, George Wells, Micere Thuku, Candyce Hamel, Julian Moran, D. Moher, P. Tugwell, Vivian Welch, Elizabeth Kristjansson, David A Henry
British medical journal