User talk:Pentograf

Hello, I'm Materialscientist. I noticed that you added or changed content in an article, but you didn't provide a reliable source. It's been removed and archived in the page history for now, but if you'd like to include a citation and re-add it, please do so. You can have a look at the tutorial on citing sources, or if you think I made a mistake, you can leave me a message on my talk page. Thank you. Materialscientist (talk) 18:50, 19 February 2020 (UTC)