Why do writers decide to use one source rather than another? Sources serve different purposes, so part of evaluating sources involves deciding what you need the source to provide for your research project. You may need background information or context that your audience will need to follow your writing; explanations of concepts unfamiliar to your audience; verbal and visual emphasis for your points; authority or evidence for your claims, which can help you create your own authority; other perspectives on your topic; or counter-examples or counter-evidence that you need to consider.

As you begin to work with your sources, make notes in your research log about why you plan to use a particular source. At the same time, you should also begin your working bibliography.