This tool finds all pages and categories in a category tree in language X. Then, it checks all of these categories in other languages, and gets pages with a language link back to X there. It lists all pages in X that are not in the original category tree, but in the tree equivalent in other languages.
Wikipedia.
Category, depth
External depth (>0 gets more pages, but is much slower) Temporarily disabled
(Example: French scientists on fr.wikipedia)
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SELECT DISTINCT page_id FROM page WHERE page_namespace=14 AND page_title IN ('')