 The combination of Mbass, Medline, Web of Science Core Collection, and Google Scholar performed best, achieving an overall recall of 98.3 and 100% recall in 72% of systematic reviews. 16% of the included references, 291 articles, were only found in a single database, Mbass produced the most unique references. This article was authored by Witcher Embraer, Melissa L. Refleffson, Jace Kleinen, and others.