There are many signs that reveal a source might not be credible. First of all, you need to check if has an author (it might be physical people or an association, company etc). Then, have a look at the information, it is well-developed, organized and complete. Check writing style, if ideas are coherent and if there are grammar or vocabulary mistakes. - Date: make sure it is included not only the creation date but if there is any update or new material. - Domain: if it is a .com. org web page.
