The following article (preprint) was shared on arXiv earlier today.
Nees Jan van Eck
We present a large-scale analysis of the accuracy of citation data in the Web of Science and Scopus databases. The analysis is based on citations given in publications in Elsevier journals. We reveal significant data quality problems for both databases. Missing and incorrect references are important problems in Web of Science. Duplicate publications are a serious problem in Scopus.
Direct to Full Text Article
6 pages; PDF.