Sources
Sources and link checks
Every value on the site points to one of the documents below by a stable identifier.
How it works We check links automatically. Responds — the document is reachable. Blocks bots — the publisher’s server (e.g. Wiley for DOI links) rejects automated requests even though the link works in a browser; we cannot confirm it by machine and say so plainly rather than mark it as fine. This is separate from checking whether a given number actually appears in the document.
Rank Primary — the document where the value was established. Secondary — a summary table reprinting values from other reports; convenient, but not where the value was set. We distinguish them because citing a summary as a primary source is a common and fair objection to databases.