Check one citation by hand
If there is a DOI, open https://doi.org/ and the identifier. The page you land on should show the same title, the same lead author, and a compatible year. If there is no DOI, search the title in quotation marks in Crossref or Google Scholar, then compare authors and year. A title that appears only inside the document you are checking is a bad sign.
Write down which of these you found: the work exists and the details match; the work exists but the year, pages, or DOI are wrong; nothing matching turns up; or you cannot tell because the title is too short or the journal is outside these indexes.
Check a list with RefCheck
The form on this page, and the box on the RefCheck homepage, run that comparison for each line. Crossref and OpenAlex come first. PubMed and Europe PMC are added for biomedical references, arXiv for preprints, DBLP for computer science, DataCite for datasets, and Open Library and Google Books for books. Semantic Scholar is included. Retraction signals come from Retraction Watch data in Crossref, and from PubMed and Europe PMC.
The four verdicts are real, real with errors, likely fabricated, and unconfirmed. “Unconfirmed” is common for Chinese-language journals that are not in these databases, for a preprint posted in the last few days, and for some books. It is not a synonym for fake. When a Chinese reference cannot be confirmed, RefCheck links out to CNKI, Wanfang, and Baidu Scholar so you can look there yourself.
What this will not decide
RefCheck does not score plagiarism, does not log into CNKI, and does not search court opinions. It also does not tell you that the cited paper says what your sentence claims. After a match, open the paper if the claim matters.
The Chinese how-to is 怎么核查参考文献. Style-specific notes are on the APA, IEEE, and Vancouver pages. Those pages still check existence, not punctuation.