Turkey, Worked Out. is built from the articles below — this site’s own reporting, written at the same desk, not an outside authority. The book does not quote them; for the numbers it is about, no authority publishes a figure to quote, which is why every chapter shows its working.
Where a claim rests on something other than this reporting — a government rule, a carrier’s published terms, an official advisory — the book names that source in the line itself rather than leaving you to guess.
Last checked means someone re-read the article against its sources on that date. Most pages carry only a publication date, and that is the honest state: it is not a claim that nothing has changed since.