What sources will convince your readers (and your professor!) that you have thoroughly investigated your research question, read what other experts think, and contribute to your argument and findings? Often, peer-reviewed sources will be a big part of those sources.
It can be difficult to verify information on the web or on social media. Posts and articles are often written to be sensational or to misinform or confuse readers. Mike Caulfield outlines a simple and effective 4-step fact-checking method, "SIFT." The method is outlined here and links to short videos give more information.
2. Investigate the Source using Google or Wikipedia.
3. Find Better Coverage of the event or news in the post or article
4. Trace Claims, Quotes, and Media back to the Original Context.