User talk:71.222.186.250

April 2020
Hello, I'm Materialscientist. I noticed that you made a change to an article, Trapdoor mechanism, but you didn't provide a source. I’ve removed it for now, but if you’d like to include a citation to a reliable source and re-add it, please do so! If you think I made a mistake, or if you have any questions, you can leave me a message on my talk page. Thanks. Materialscientist (talk) 07:01, 24 April 2020 (UTC)
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