There's a recent article published in Research Evaluation analyzing MDPI's self-citation rates. The author argues that MDPI's self-citation rate is anomalously high relative to leading journals in the same field, and that this is indicative of predatory publishers.

The article contains this paragraph:

The high rate of self-citations of the journal Sustainability is coherent with data that the journal itself provided in its bibliometric review over the period 2009–18 (https://www.mdpi.com/2071-1050/10/5/1655), showing that Sustainability ranks first in citing journals (2,496 cites) very much over the Journal of Cleaner Production that occupies second position (658 cites) in this bibliographic review. It is remarkable that in the aforementioned bibliometric study over the period 2009–18, the first 30 positions in the citation ranking were occupied by journals from the same publisher (#3 Energies, #8 Water, #23 International Journal of Environmental Research and Public Health, #24 Remote Sensing and #30 IJGI). Copiello (2019) also analysed the citations and self-citations of articles published in the journal Sustainability in 2015 and found that the journal had a higher self-citation level than expected.

The cited website is actually an article published in Sutainability. The full citation is

Tang, M.; Liao, H.; Wan, Z.; Herrera-Viedma, E.; Rosen, M.A. Ten Years of Sustainability (2009 to 2018): A Bibliometric Overview. Sustainability 2018, 10, 1655. https://doi.org/10.3390/su10051655

The way the Research Evaluation article cited the Sustainability article is clearly different from the way it cites other papers (c.f. the Copiello (2019) citation in the same paragraph), and this oblique style of citation causes the citation to not show up in the references section. I'm guessing that this is happening because the author believes Sustainability is predatory and therefore does not want to add to its citation counts.

I am wondering if this is ethical.

Update: OUP published an "expression of concern" to say that the Research Evaluation article is being reviewed for unnamed "issues".

Update #2: the expression of concern is resolved now, and the above paragraph remains in the article.

  • 5
    I agree that this looks like an attempt to cite without giving credit. Commented Aug 27, 2021 at 3:12
  • 3
    I wonder how that article passed peer-review. I'm not a big fan of MDPI[1] but the article has a strong smell of confirmation bias. The MDPI response actually has a few valid points. [1] I review for them but won't submit manuscripts and won't become editor of a special issue despite their numerous invitations.
    – user9482
    Commented Aug 27, 2021 at 6:43
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    @Roland you're not the only one with that impression. One particularly egregious problem with that paper is that it calls MDPI's 1000-2000 CHF APC "high", yet it is published open access in a journal that charges EUR 2678. It's pretty ironic. I know some people who are thinking of writing a sarcastic comment that Oxford University Press must be a predatory publisher that only accepted that article because the author paid ...
    – Allure
    Commented Aug 27, 2021 at 6:48
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    @Roland and Allure 'the first 30 positions in the citation ranking were occupied by journals from the same publisher' doesn't just smell of confirmation bias, it's downright false. Could be a straightforward typo and they meant to say "six of the first 30" or similar, but still... Commented Aug 28, 2021 at 13:04
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    Interesting. I've been seeing a lot of oblique citations of articles presenting a competing view to the authors' recently, in another field. IMO, unless the illegitimacy of a cited work is quite firmly established, it should be cited properly. If it appears to be legitimate work, oblique citation is improper, even if the conclusions appear likely to be incorrect. (Caveat: haven't read the papers.) Commented Sep 7, 2021 at 1:07

1 Answer 1


No, if you're going to cite an article, you should do so in the standard manner used by your publication or by one of the standards used in your field (say, if you're publishing privately, such as on your own website). Merely linking a page as an in text citation, without naming the author(s) or listing it in your references is simply a "no go".

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