"Searching is a term used to describe the methods by which you identify evidence to be included in your review. Potential resources include bibliographic databases, volumes of specialist journals, reference lists from retrieved articles, research registers, government databases, newspapers and/or experts in your particular field."
Dundar, Y., & Fleeman, N. (2014). Developing my search strategy & applying inclusion criteria. In A. Boland, M.G. Cherry R. Dickson (Eds.), Doing a systematic review: A student's guide (pp.37-59). London: SAGE.