According to Bishop, most people involved in review mills are seeking to boost their citation numbers. These guide university decisions around hiring, promotions and tenure, and influence university rankings and funding decisions. The more that citation numbers are used as a metric of academic success, “the more people will try to game the citations”, she says.
Evidence for this comes from the observation that some people who provide duplicate reports are also habitual self-citers. Fabian Wittmers, a marine biologist and science sleuth at Oregon State University in Corvallis, mentions the engineer Rabiul Awual as one example of this phenomenon. Wittmers says that Awual’s high citation count — his work has been cited nearly 43,000 times according to Google Scholar — is partly due to a long-standing self-citation habit. In a now-retracted study about caesium removal from waste water6, for instance, Awual and his co-authors cited their own research 123 times — Wittmers considers 10–15 self-citations per paper to be the acceptable limit. The retraction notice, issued in October 2025, notes that the citations to Awual’s research, most of which were added at the revision stage, were of “either borderline relevance or no relevance whatsoever to the article”, and calls this practice “a violation of publishing ethics”. The notice also says that the authors disagree with the grounds for the retraction.
When contacted about their reasons for disagreeing with the retraction, co-author Nazmul Hasan asked Nature to refrain from sending them e-mails. Other co-authors, including Awual, did not meaningfully reply to requests for comment, instead responding with hostility and profanity.
Many more citations could stem from Awual’s review practices, too. Public reviews that Awual has written for papers in MDPI journals reveal that he often uses the same statements across reports and includes citation requests to his own research. Wittmers says that he has discovered dozens of studies by other researchers in Elsevier journals that cite large numbers of Awual’s studies. The reviews for those studies aren’t public but Wittmers suspects that these were reviewed by Awual or his collaborators.
One 2022 study7 in the journal Food Chemistry about the structural properties of dough in steamed bread, for instance, cites four of Awual’s papers about wastewater treatment. “This is not a one-off situation. There’s multiple papers in Food Chemistry where papers by Awual were cited that make no sense,” says Wittmers.
Wittmers suspects that for Awual and his collaborators, these kinds of review practice might be necessary to get their studies cited, because he deems many of the papers to be of poor quality. For instance, in a 2025 PubPeer post, Wittmers reported evidence of image duplication in six of Awual’s studies. “No one wants to cite these paper-mill products,” Wittmers says. “So you need to request that they get cited. And that’s why you review a lot.”
When Awual was invited to comment on Wittmers’ allegations of self-citation, review milling and image duplication, he asked Nature to stop sending “foolish” e-mails.
One author of a study in an Elsevier journal — who requested anonymity to avoid possible conflicts with reviewers or publishers — says that they felt coerced into citing Awual’s studies because of the anonymous review that they had received. After generic suggestions that the title be rephrased and that the study’s novelty be explained in the introduction, the review contained numerous reference requests. The reviewer concluded with a request to see the revised manuscript, implying — the author thought — that they might recommend rejecting the paper if the requests weren’t fulfilled. “I felt pressured by the reviewer,” the author says.
They say that they’ve asked the journal to review the irregular references and that they’ll alert journal editors if they encounter similar reviewer reports in the future. In general, the author says, they’ve seen a worrying increase in incoherent reviewer reports that seem to be referring to entirely different manuscripts. “It seems that many journals do not perform even minimal checks on the coherence and relevance of peer reviews, leaving scientists vulnerable to inadequate reviewing practices,” they note.
When asked for comment about Elsevier’s handling of reviewer reports, a spokesperson said that the publisher’s policies address citation manipulation by reviewers and that the publisher has training in place to help editors to recognize such practices. “Reviewers should not suggest citations to the reviewer’s (or their associates’) work unless the suggested citations are for genuine scientific reasons,” note the policies. “Editors may remove citations that, in their view, are inappropriate from reviewer comments.”
Why Awual was invited to review for journals outside his scientific expertise is unclear. In general, Wittmers suspects that review mills often make an editor’s job easier, because they struggle to find reviewers among an increasingly overworked academic workforce. Review mills might respond quickly to review requests, helping journals to reduce the time spent on article reviews.
Nature journalists asked Springer Nature for comment on its processes for dealing with coercive peer-review practices and promoting academic integrity. A spokesperson said that the publisher has been working to identify and prevent review-mill activity by examining peer-review content and investigating networks of compromised individuals.
“For cases where we can document repeated attempts to manipulate citation practices, individuals are suppressed from acting as reviewers in future and may be subject to further sanctions, such as being blocked from publishing in our journals,” the spokesperson says. Authors can report coercive citation requests to a journal’s editor-in-chief or to the publisher, and editors should inform their relevant publishing contact, they added.
