By far this atlas's largest single source kind: collaboratively edited online encyclopedia entries, principally Wikipedia, cited for biographical facts about linguists, descriptive facts about languages, scripts and language families, and background on historical linguistic events. Belongs here: any citation to a live, publicly editable encyclopedia article. Does not belong here: a citation to a peer reviewed journal article, an academic reference work with a named edition and year, or a general (non-collaborative) encyclopedia such as Britannica, each tracked as its own separate source kind so a reader can judge a fact's evidentiary weight from its citation alone rather than treating every online reference as equivalent.