When you're evaluating a source you found on the Web, don't just look at the source. There are sites that may look very professional and credible that are actually promoting a certain agenda or viewpoint. If you are unfamiliar with the source, it is always a good idea to open a new tab and do a Web search on the source and/or the organization that is providing it. This process is called Lateral Reading - in addition to reading down the Webpage, you open additional tabs and go outside of your page to see what others are saying about it.
Use this series of brief videos, from Mike Caulfield at Washington State University, to see how Lateral Reading works.