Examples
Worked examples
- Is an instance
Three journals whose editors mutually request the addition of citations to each other's journals during peer review, producing a tight, disproportionate citation triangle visible in a citation-network map.
- Is an instance
A 2026 case reported by C&EN in which fabricated author identities — fictitious researchers with invented institutional affiliations in several countries, used partly to claim article-processing-charge waivers — were used across roughly 20 chemistry papers as vehicles for coordinated, purchased citations (reported price on the order of $5-10 per citation); the publishers named in the report stated they were investigating.
Counter-examples
Looks similar, but isn't
- Not an instance
A specialist subfield where a small number of researchers cite each other often because they are genuinely the only people working on that narrow topic is ordinary co-citation, not a cartel — density alone is not the criterion; disproportion relative to the group's actual scholarly overlap is.
- Not an instance
An author citing their own earlier, directly relevant work is self-citation, a distinct and much more common pattern; self-citation becomes a red flag in the same suppression review Clarivate applies to cartels, but it is a different mechanism (one author citing themselves) from a cartel (a coordinated group citing each other).
Editorial commentary
A citation cartel is a coordinated pattern of over-citation among a group of authors, editors, or journals, undertaken specifically to inflate citation-based metrics rather than because the citations reflect the underlying scholarship. Cartels can operate at three levels: individual authors forming mutual citation pacts; journals engaging in cross-journal “citation stacking” (reciprocal over-citation between two or a small ring of journals); or editorial boards steering authors toward citing a partner journal during peer review. Because the underlying evidence is a statistical pattern rather than a single document, suspicion of a citation cartel is not proof of one — a finding requires bibliometric network analysis showing citation density between the alleged members that is disproportionate to their genuine scholarly overlap, not simply frequent mutual citation.
Distinguishing a cartel from co-citation and self-citation
Two adjacent, legitimate patterns are routinely confused with citation cartels:
- Co-citation is ordinary scholarly clustering — researchers working in a narrow subfield naturally cite the small set of other researchers active in that same subfield repeatedly, because there is genuinely little else relevant to cite. This produces citation density but is not coordinated and is not undertaken to game a metric.
- Self-citation is an author or journal citing its own prior work. It is common, often legitimate (building directly on one’s own earlier findings), and is tracked separately from cartel behaviour — Clarivate’s Journal Citation Reports (JCR) reports each indexed journal’s own self-citation rate alongside its Journal Impact Factor. Clarivate’s analysis of the 2014 JCR Science Edition found 85% of indexed journals had self-citation rates at or below 15%; an earlier 2002 review found 82% of SCI-edition journals at or below 20%. A high self-citation rate is a distinct pattern from citation stacking between two or more separate journals, though both feed into the same JCR suppression review.
What distinguishes a cartel from either of these is coordination and disproportion: the citation flow is directed, concentrated among a defined group, and out of proportion to that group’s actual scholarly relevance to each other — not simply that citation counts between the parties are high.
How publishers and Clarivate detect coordinated citation manipulation
Detection relies on bibliometric network analysis: mapping citation flows across a set of journals or authors and identifying clusters where the density of mutual citation is anomalous relative to the group’s field, size, and publication volume. Clarivate — which produces the JCR and the Journal Impact Factor — periodically reviews journals for exactly this kind of anomalous self-citation or reciprocal “citation stacking” pattern as part of its JCR suppression process; journals found to rely on cartel-like citation patterns for an outsized share of their Impact-Factor-directed citations have been temporarily suppressed from the JCR. Clarivate deliberately does not publish its exact suppression thresholds, specifically to make the criterion harder to game.
Consequences
The central practical consequence is Impact Factor suppression: a journal found by Clarivate to have manipulated its metrics through citation stacking or excessive self-citation can be excluded from that year’s JCR listing, removing its Journal Impact Factor from public view for that period. Beyond metric suppression, coordinated citation manipulation involving fabricated authorship — as in cases where cartels have been built around invented author identities — can also trigger publisher-level investigations and retractions once the underlying fabrication is confirmed, distinct from the metrics-suppression consequence itself. Editors and bibliometricians treat an anomalous citation-network cluster as grounds to open an investigation, not as a finding in itself — the label “citation cartel” is properly applied only once that investigation substantiates coordination, not at the point suspicion is first raised.
References
- Fister, Fister & Perc (2016), “Toward the discovery of citation cartels in citation networks”
- Clarivate, “A Refresher Course on JCR Journal Suppression Policies” and JCR suppression policy documentation (current edition)
- C&EN (cen.acs.org), reporting (Feb 2026) on fabricated-author citation cartels in chemistry publishing, investigator Anna Abalkina
Also known as
citation ring · citation stacking
Machine-readable encodings
Use in your systems
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