  Modern bibliographic databases provide the basis for scientific research and
its evaluation. While their content and structure differ substantially, there
exist only informal notions on their reliability. Here we compare the
topological consistency of citation networks extracted from six popular
bibliographic databases including Web of Science, CiteSeer and arXiv.org. The
networks are assessed through a rich set of local and global graph statistics.
We first reveal statistically significant inconsistencies between some of the
databases with respect to individual statistics. For example, the introduced
field bow-tie decomposition of DBLP Computer Science Bibliography substantially
differs from the rest due to the coverage of the database, while the citation
information within arXiv.org is the most exhaustive. Finally, we compare the
databases over multiple graph statistics using the critical difference diagram.
The citation topology of DBLP Computer Science Bibliography is the least
consistent with the rest, while, not surprisingly, Web of Science is
significantly more reliable from the perspective of consistency. This work can
serve either as a reference for scholars in bibliometrics and scientometrics or
a scientific evaluation guideline for governments and research agencies.
