So for some reason I stumbled upon asking Bard/GPT for a reccomendation of a biography on Gregory of Nyssaa as a test, I wast looking for one but it turns out t

So for some reason I stumbled upon asking Bard/GPT for a reccomendation of a biography on Gregory of Nyssaa as a test, I wast looking for one but it turns out there really isn't on, at least in English. This gives them the tendency to Hallunicate. Sure enough tried on Gemini and get a fictional biography Saint Gregory of Nyssa: An Intellectual Biography by Rowan Williams (The former Archbishop of Canterbury). I think it's making this up based on the book St Gregory of Nazianzus: An Intellectual Biography but that is by John McGurkin. The other ones it recommends are Gregory of Nyssa by Lewis Ayers (A real author, no such book), Gregory of Nyssa: The Life and Works of a Cappadocian Father, and Gregory of Nyssa: Asceticism and Anthropology by Sarah Coakley. This last one is the closest to actually existing since she edited the book Re-Thinking Gregory of Nyssa which is a collection of essays on him. So it didn't make up any authors at least, but did make up some books. It will happily make up ISBNs for them if I ask and even provide links to Amazon, that of course go to other books. Asking for a book about any other figure notable enough to have a Wikipedia page but obscure enough to not have any existing book written about them will do the same thing, I tried it out with multiple signers of the Declaration of Independence for instance.