Ghost references more frequent in Dutch scientific articles

De Groene Amsterdammer, in collaboration with Utrecht University’s Data School, analysed over 136,000 academic articles. The findings reveal that, over the past three years, hundreds of researchers affiliated with Dutch universities have published articles containing so-called "ghost references": citations to non-existent publications.

Sharp increase
In 2023, just one in every 1,400 articles contained a phantom reference; by 2026, this had risen to one in every 200. The proportion of articles containing references to non-existent sources has therefore increased sevenfold over the past three years.

Ghost references occur in virtually all academic disciplines, reports De Groene Amsterdammer. They usually look legitimate and sound convincing, which makes them difficult to spot.

The weekly magazine spoke to several academics who had cited non-existent sources. According to them, this happened unintentionally. They asked a chatbot an innocent question, such as whether they might have overlooked an important source.

One of the authors topping the list of phantom references is Peter Nijkamp, Professor Emeritus of Regional Economics, who came under fire over a decade ago for self-plagiarism. Over twenty phantom references were found in five of his recent articles. Nijkamp told De Groene Amsterdammer he feels he has been duped by search engines.

The research shows that academics at Wageningen University have the highest number of articles containing non-existent references. The university emphasises that responsibility lies primarily with the authors and journals, but will investigate whether internal guidelines and control mechanisms need to be tightened up.

According to a survey by academic publisher Elsevier, around 58 per cent of researchers use some form of artificial intelligence. AI is mainly used to search for recent studies and gather literature, the researchers themselves say.