They explain in the article what they consider a proper citation, an erroneous one and an hallucination, in the section "Defining Hallucitations". They also say than they have many false positives, mostly real papers who are not available online.
Thad said, i am also very curious of the result than their tool, would give to papers from the 2010's and before.
Thad said, i am also very curious of the result than their tool, would give to papers from the 2010's and before.