ChatGPT (the free version) makes up citations that don't exist.
ChatGPT might give you articles by an author who usually writes about your topic, or even identify a journal that published on your topic, but the title, page numbers, and dates are completely fictional. This is because ChatGPT is not connected to web search, so has no way of identifying actual sources.
You can try to see if any are valid by searching in the library or Google Scholar but chances are the sources do not exist.
It's better to use ChatGPT for tasks like these:
It's not designed to be a search engine. Use OneSearch, Google Scholar, or databases for your discipline instead.
Another option for searching the web is Perplexity AI. It combines a language model with a search engine and provides links to its sources so you can fact-check. It doesn't include all the scholarly resources you would find in Library Search or Google Scholar, but it can be a complementary tool for finding web search results with natural language.
Source: Nicole Hennig, University of Arizona