Sources policy

Order of preference

1. Clinical guidelines and recommendation bodies (for example USPSTF, ESC/EAS, WHO guidelines).

2. Public-health and government health agencies (WHO, NIH institutes such as NIDDK and NHLBI, MedlinePlus, NHS, FDA).

3. Peer-reviewed research indexed in PubMed — preferring systematic reviews, meta-analyses and consensus statements over single studies.

4. Manufacturer documentation, used only for what a device or feature does, never for health claims.

What we do not use

Blogs, marketing material, forums and AI-generated summaries are not used as sources. We never invent or approximate a reference; if a claim cannot be supported by a verifiable source, it is not published.

Every page shows its sources

Each Health Library page lists the sources behind its factual claims, with links. A page without sources cannot be published: our publishing system blocks it automatically.

Source age

We record source dates. An older source is a signal to review, not automatic proof that it is outdated — definitions, reference documents and fundamental studies can remain valid for many years. What matters is whether the content still reflects current guidance.

Link checks

Source links are checked regularly. Each link is recorded as reachable, redirected, temporarily unavailable, permanently unavailable (only after repeated failures) or requiring review. Link checks never change article content automatically; an editor reviews any problem.

Updates and corrections

Pages are reviewed when major guidance changes and are flagged for review after 12 months. Readers can report errors through our contact page; confirmed errors are corrected and the page's last-updated date changes.