  We present a large-scale comparison of five multidisciplinary bibliographic
data sources: Scopus, Web of Science, Dimensions, Crossref, and Microsoft
Academic. The comparison considers scientific documents from the period
2008-2017 covered by these data sources. Scopus is compared in a pairwise
manner with each of the other data sources. We first analyze differences
between the data sources in the coverage of documents, focusing for instance on
differences over time, differences per document type, and differences per
discipline. We then study differences in the completeness and accuracy of
citation links. Based on our analysis, we discuss strengths and weaknesses of
the different data sources. We emphasize the importance of combining a
comprehensive coverage of the scientific literature with a flexible set of
filters for making selections of the literature.
