It's important to remember there's a human at the other end of every source. You need to be a critic when deciding what sources will be useful for you. Keep in mind that this guide below is just that--a guide. Not every source is going to fit perfectly in every category, but it's important to be aware of every source's flaws and to move forward accordingly. If you're still not sure if a source will work for your needs, ask your instructor or a librarian.