How the resolver works
For every row in your study list that has a DOI, Systematic Review asks a sequence of open, public services whether a legal full-text PDF exists. We never scrape publisher pages, bypass login walls, or use grey-market mirrors.
The resolver waterfall
The lookup is deterministic — same DOI, same path, every run:
DOI in │ ├─ 1. Unpaywall → legal OA link by DOI? │ └─ yes → save PDF, label "Unpaywall" │ ├─ 2. Europe PMC (by DOI) → open full text? │ └─ yes → save PDF, label "Europe PMC" │ ├─ 3. Europe PMC (by PMC ID) → PMC mirror? │ └─ yes → save PDF, label "Europe PMC · PMC" │ └─ 4. none → status "No open access found"
When a PDF isn't found
Two outcomes are not the same and Systematic Review records them separately:
- No open access found — every resolver returned no legal full text. The article likely sits behind a paywall. Free-tier accounts are not charged a download slot for this case.
- Error — a network or API timeout interrupted the lookup. You can retry the row from the toolbar.
Troubleshooting
The DOI looks right but nothing resolves
Confirm the DOI on doi.org. If the page loads but no OA badge appears anywhere, the publisher has not deposited an open copy. Try your university library or the author's institutional page.
I have the PMC ID but the row shows missing
Add the PMC ID to your CSV column pmcid (e.g. PMC1234567) and re-run the row. Step 3 of the waterfall will pick it up.
Filenames are inconsistent on Windows
Systematic Review strips characters that Windows and macOS reject (< > : " / \ | ? *), collapses whitespace, and caps length. If your downstream tool expects a stricter pattern, rename via export rather than editing files on disk.