Query the paper's DOI in Unpaywall to see the open-access locations recorded for that article, then check CORE for repository copies if Unpaywall lists no location, and confirm the copy you find matches the version you intend to cite. Unpaywall records describe open-access locations associated with a DOI, including host type, version, license information when available, and a selected best open-access location. That record tells you where a legal open copy has been recorded and what version it is, so read the version field before you rely on the text.
- Start with the DOI. Enter the article's DOI in Unpaywall. A result with a listed open-access location gives you a host and a version to inspect; a result with no location means this route has not recorded one, so move to the next step.
- Check CORE for repository copies. CORE aggregates open-access research outputs and offers discovery services, data access, and tools for finding repository copies of scholarly work. Search there for the article title or DOI to locate a repository copy.
- Compare the version to the one you are citing. Unpaywall records include version information, so check whether the copy is the same version as the passage, figure, or page you plan to cite. If the versions differ, cite the version you actually read and note the difference.
- Check open-access journal records when relevant. DOAJ provides searchable article and journal records for open-access journals that meet its inclusion criteria, which helps when the paper appeared in an open-access journal.
- Record what you used. Note the host, the version, and the license shown in the record so your reference list and any shared copy point to the same source.
If neither Unpaywall nor CORE returns a usable copy, the open-access status of that paper remains unresolved through these routes; ask your library or the authors for a copy before your deadline rather than relying on an unverified file.