Haddaway NR, Collins AM, Coughlin D, Kirk S.
The Role of Google Scholar in Evidence Reviews and Its Applicability to Grey Literature Searching.
PLoS One. 2015 Sep 17;10(9):e0138237
A very interesting article that touches upon GS in several contexts, including tracing its improvements over the years. The authors also discuss the debates about how GS works and then also about how useful it is in finding grey literature for conducting evidence reviews. The article concludes that GS is indeed a useful supplement in searches for evidence, particularly grey literature so long as its limitations are recognised. The authors recommend that the assessment of results from Google Scholar, should move on to recording snapshots of all viewable search results: i.e. the first 1,000 records, instead of the first 50 that most Systematic Review authors use. They feel that this change in practice could significantly improve both the transparency and coverage of systematic reviews, especially with respect to their grey literature components. Happy reading!