A systematic review is a review of a clearly formulated question that uses systematic and explicit methods to identify, select, and critically appraise relevant research, and to collect and analyze data from the studies that are included in the review. (Definition from the Cochrane Collaboration.)
Cochrane Library provides systematic reviews that are in-depth, comprehensive, and of a high standard.
Use the advanced search to input your keywords. In your results, reviews are indicated by the 'review icon' at the right of each result.
Alternatively, choose to search the Cochrane Database of Systematic Reviews (CDSR) by selecting 'Search CDSR' from the Cochrane Reviews tab on the main page of Cochrane Library.