From Retro CDN
The MediaWiki software automatically recognizes inline ISBNs. For example, the wikitext ISBN 0-12-345678-9 becomes ISBN 0-12-345678-9 (the dashes are optional), which corresponds to Special:Booksources/isbn=0123456789. This creates a link to a special page on book sources, where readers can obtain more information about getting a copy of that particular book.
This function may be useful in helping users to determine which book(s) were used as references for a specific article, and because it provides links to various online bookstores. However, ISBNs only identify a specific edition of a book, and the reader will not see the full range of the versions of the book for sale. Therefore, do not use ISBNs alone as a means of identifying books; add a full and proper citation in addition to the ISBN.