User talk:Abderrahman El Yessa

Hello, I'm Materialscientist. I noticed that you made a change to 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! If you need guidance on referencing, please see the referencing for beginners tutorial, or if you think I made a mistake, you can leave me a message on my talk page. Thank you. Materialscientist (talk) 10:25, 3 October 2017 (UTC)