Reference sources, such as encyclopedias, handbooks and manuals, are great options to do some background reading on your topic. These sources will give you broad background information on your topic.
Reference sources do not represent original research like journal articles. These sources can help you quickly learn about your topic before you dive into the research literature.
Use textbooks and reference books to answer background questions. These types of questions are broad and when answered provide basic foundational knowledge. Background questions often begin with "what" or "when".
Reference databases are a good starting point. All of these sources are credible and authoritative. When searching for reference sources, keep your keywords simple. For instance, search mental health or Bipolar Disorder I.