"A systematic review is a literature review that is designed to locate, appraise and synthesize the best available evidence relating to a specific research question to provide informative and evidence-based answers. This information can then be combined with professional judgement to make decisions about how to deliver interventions or to make changes to policy."
Dickson, R., Cherry, M.G. & Boland, A. (2014). Carrying out a systematic review as a Master's thesis. In A. Boland, M.G. Cherry R. Dickson (Eds.), Doing a systematic review: A student's guide (pp.3). London: SAGE.