Some books that are referenced on a Wikipedia page are removed as references in later versions of the page. When this happens, the reference is no longer applicable for the book, so the following should be done:
[x] Periodically go through Wikipedia events. For each, check the reference section of the Wikipedia page to make sure that the DOI of that event is still referenced on the page.
[x] If the reference is no longer valid, mark it as a deleted event.
[x] Periodically check deleted Wikipedia events to see if the book reference has been restored.
Some books that are referenced on a Wikipedia page are removed as references in later versions of the page. When this happens, the reference is no longer applicable for the book, so the following should be done: