De Groene Amsterdammer, together with the Data School at Utrecht University, examined more than 136,000 scientific articles. The study found that hundreds of researchers affiliated with Dutch universities had published articles containing “ghost references”: citations to publications that do not exist.

Sharp increase

In 2023, one in every 1,400 articles contained a fake reference; in 2026, the figure was one in 200. The share of articles containing references to nonexistent sources has therefore increased sevenfold over the past three years.

Phantom references occur in almost every field, De Groene Amsterdammer reports. They usually look legitimate and sound convincing, making them difficult to spot at times.

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

Also at the top of the list of authors with ghost references was emeritus professor of regional economics Peter Nijkamp, who came under scrutiny more than a decade ago for self-plagiarism. More than twenty ghost references were found in five of his recent articles. Nijkamp says he feels misled by search engines, he told De Groene Amsterdammer.

Wageningen

The study found that scientists at Wageningen University had the largest number of articles containing nonexistent references. The university emphasizes that responsibility lies primarily with the authors and journals, but it will investigate whether internal guidelines and control mechanisms need to be strengthened.

According to a survey by scientific publisher Elsevier, around 58 percent of scientists use some form of artificial intelligence. The scientists themselves say AI is used primarily to search for recent studies and compile literature.

This article was translated using AI-assisted tools and reviewed by an editor.