With an h-index of 75, computer scientist Thippa Reddy Gadekallu ranks among the world’s most highly cited researchers. But the speed and means of his ascent to those lofty heights of scholarship has been as remarkable as the achievement itself.
In less than a decade, Gadekallu, a professor at Zhejiang A&F University in China, has managed to bootstrap himself from scientific obscurity by collaborating with colleagues around the world who cite each other’s work in ways that have raised questions. In some years, Gadekallu received more citations than Yoshua Bengio, a pioneer in artificial intelligence and the top-rated computer scientist on Google Scholar.
Earlier work uncovered a network of reviewers on papers Gadekallu edited who frequently suggested adding citations to his work. A closer look by Retraction Watch shows the impact of that strategy on Gadekallu’s h-index, and reveals additional possible collaborators in the network.
“Man, this is crazy,” said Vincent Larivière, an information scientist at the University of Montreal, whom we asked to review the metrics. “These numbers are definitely suspect.”
The h-index is based on citation rates, and growth becomes more difficult with each new paper. Extraordinarily prolific researchers, such as John Ioannidis, have experienced single year jumps as high as 16, but yearly increases in the single digits are more typical.
David Robert Grimes, a Retraction Watch Sleuth in Residence, examined the citation records of Gadekallu and his closest collaborators, and found that, in 2019, Gadekallu’s h-index jumped 17 points, from 10 to 27. The following year, it jumped 23 points, and then 19. Matching Ioannidis’s career high, Grimes said, “is kind of like matching Usain Bolt’s 100-meter time.”
Repeating the feat three times in a row? “You either have a truly exceptional scholar or something else is going on,” Grimes said.
| Year | Number of publications | Number of citations | H-Index |
| 2014 | 1 | 25 | 1 |
| 2016 | 8 | 63 | 4 |
| 2017 | 7 | 280 | 10 |
| 2018 | 2 | 57 | 10 |
| 2019 | 1 | 6 | 10 |
| 2020 | 28 | 4057 | 27 |
| 2021 | 49 | 4906 | 50 |
| 2022 | 83 | 7531 | 69 |
| 2023 | 93 | 3987 | 74 |
| 2024 | 82 | 1883 | 75 |
| 2025 | 87 | 239 | 75 |
Grimes’s work has revealed that his network includes dozens of coauthors spread around the world. Like Gadekallu, Grimes found, his most frequent collaborators have experienced remarkably steep increases in their h-indices, raising the question of whether such metrics should continue to be relied upon.
Over the course of several emails with us, Gadekallu admitted that he typically leaned on collaborators to conduct peer reviews, but insisted that he has never participated in any intentional manipulation.
“I completely understand why it might look concerning from the outside, but I categorically deny any behind the scenes coordination, pressure, or exchange regarding citations,” he wrote.
Hung-Wen Chiu’s experiences tell a different story.
In April 2021, Chiu, a biomedical engineer at Taipei Medical University in Taiwan, submitted a new paper to PLOS One. The paper described a method to automatically classify medical images of different body parts that had been captured on different types of machines.
PLOS One’s editorial board is made up of thousands of volunteer editors from around the world. Chiu’s paper was assigned to Gadekallu, then at the Vellore Institute of Technology in India, who delegated it to two peer reviewers.
The peer review comments Chiu received several weeks later were brief and generic. “Discuss the limitations of the current work,” the first reviewer suggested. “Typo’s [sic] in the whole paper,” the second reviewer said.
But in one area they offered more precision: citations. Both reviewers felt Chiu’s paper should reference two of Gadekallu’s own articles and two others from one of Gadekallu’s collaborators. One provided a link to the Google Scholar profile for the collaborator: “Visit this profile and cite related papers.”
The papers were broad, descriptive surveys with little analysis and lots of citations. None was particularly relevant to Chiu’s study, but he agreed to add one, which at least had a section on medical imaging. “Inappropriate,” was how Chiu described the request in an email to us.
Five days after submitting his revisions, Chiu’s paper was accepted. “We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication,” Gadekallu wrote.
Chiu’s experience with Gadekallu was hardly unusual according to Maria de los Ángeles Oviedo-García, an economist at the Universidad de Sevilla, who has reviewed Gadekallu’s history. Her review of 31 publicly available peer review reports from PLOS One and other journals finds Gadekallu’s reviewers have recommended that authors cite Gadekallu’s work on 35 occasions and the work of his coauthors on 79 different occasions.
Gadekallu has served as a reviewer on at least 949 papers, according to Clarivate’s Web of Science. At least in the reports that are publicly available he, too, has recommended that authors cite his own work. “I believe there is much more hidden than I can find,” Oviedo said.
Although Gadekallu has been linked to numerous retractions in various journals he edited, he was a productive PLOS One editor until his dismissal from that board in October 2024. Beth Baker, a spokesperson for PLOS, told Retraction Watch that an investigation around Gadekallu’s activities is still ongoing. “PLOS does not support or condone coercive citation practices,” she added.
While there’s a long history of peer reviewers gently nudging authors to cite their own work, organized citation rings, which can involve dozens of participants actively boosting each others’ metrics, emerged just over a decade ago. These schemes often distort the peer-review process with bogus reviews and irrelevant citations. Editors, too, have been implicated.
Gadekallu’s own rise as a citation powerhouse began in 2018, shortly after he completed his Ph.D. at the Vellore Institute of Technology in southern India. VIT, founded in 1984, was little known outside the region, but over the next decade it seeded the engineering literature with a raft of low-quality publications and a generation of editors who would be linked to retractions of entire special issues tarnished by evidence of peer-review manipulation.
Much of Gadekallu’s work consists of lengthy descriptive “surveys,” which typically summarize and define various fields of study. Some of these papers feature “tortured phrases” — often a hallmark of questionable research papers — while others contain irrelevant citations and seemingly impossible data, according to commenters on PubPeer.
“There is no secret to this growth other than working rigorously at the forefront of evolving fields, which naturally increases the likelihood of contributing meaningful results,” Gadekallu told us.
Gadekallu supercharged his impact by establishing a network of more than 1,000 coauthors with whom he has published more than 480 papers. One of his closest collaborators is Praveen Kumar Reddy Maddikunta, who obtained his Ph.D. from VIT the same year and remains an associate professor there. The two have published 97 papers together, helping to elevate Maddikunta’s h-index from 9 in 2017 to 55 today. Seventeen articles were retracted from a special issue he guest edited for the journal Mobile Information Systems for peer review manipulation and inappropriate citations.
| Year | Number of publications | Number of citations | H-Index |
| 2013 | 1 | 1 | 1 |
| 2015 | 2 | 22 | 2 |
| 2016 | 4 | 7 | 3 |
| 2017 | 9 | 144 | 6 |
| 2019 | 7 | 140 | 9 |
| 2020 | 21 | 3556 | 21 |
| 2021 | 30 | 2826 | 36 |
| 2022 | 29 | 4241 | 47 |
| 2023 | 22 | 1746 | 52 |
| 2024 | 14 | 624 | 55 |
| 2025 | 3 | 34 | 55 |
Some of Gadekallu’s most successful collaborators have gone on to obtain positions at universities in Europe and North America. Consider the case of Gautum Srivastava, a computer scientist at Brandon University in Canada. Between 2019 and 2024, Srivastava published 68 papers with Gadekallu, racking up thousands of citations, while his h-index rose from 9 in 2018 to 74 today. Several of his articles with members of the network have been retracted for “compromised editorial handling” and “inappropriate or irrelevant references” among other allegations.
While a steep rise in an author’s h-index can be a warning flag, it’s still not possible to identify citation rings without carefully reviewing the studies and the author’s history. “There is no test which is a smoking gun for metric manipulation,” Grimes said. “All we can detect is unusual changes, which have to be seen in context.”
| Year | Number of publications | Number of citations | H-Index |
| 2007 | 1 | 0 | 0 |
| 2011 | 3 | 95 | 3 |
| 2013 | 2 | 108 | 5 |
| 2014 | 2 | 7 | 5 |
| 2018 | 8 | 160 | 9 |
| 2019 | 32 | 3673 | 26 |
| 2020 | 78 | 4030 | 44 |
| 2021 | 152 | 7380 | 59 |
| 2022 | 136 | 5023 | 69 |
| 2023 | 159 | 3332 | 72 |
| 2024 | 116 | 2066 | 74 |
| 2025 | 59 | 143 | 74 |
Some of the context for Srivastava’s career trajectory can be seen in his work as an editor. Srivistava’s web page indicates that he has worked as an editor for at least 14 journals and guest edited more than a dozen special issues, though some of those do not appear to have ever been published.
In one special issue Srivastava guest edited with Gadekallu for Computational Intelligence and Neuroscience, 122 articles were retracted for “inappropriate citations” and “peer-review manipulation,” among other issues. In another special issue he guest edited for Computational Intelligence, 17 out of 29 articles were retracted based on a “compromised peer review process.”
In a brief phone interview, Srivastava declined to comment on his own retractions and denied participating in a citation ring. “I’m not part of anything like that,” he said. “I do have a lot of collaborators and that might have something to do with it.”
Gadekallu has himself racked up four retractions. Fang Kai, the vice dean of academics at Zhejiang A and F University, where Gadekallu is currently based, did not respond to multiple emails requesting comment.
As for Gadekallu, he does not see those retractions as indicative of his overall reputation. “While I take the publishers’ decisions on these four papers very seriously, they are isolated anomalies within a much larger body of work, and they do not account for the growth of my overall citation metrics,” he said.
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