When writing a research paper, you often begin with a broad topic that interests you (or one that has been assigned to you) that needs to be narrowed down based on the scope of your assignment.
Before you can narrow your topic, you need to have a basic understanding of it. This is where Tertiary sources (references materials) are extremely helpful. They will introduce you to a topic and make you aware of key facts, persons, places, etc. that can help you begin to focus your topic.
Some common types of reference resources include: