Background information on a topic can often be found in encyclopedias, dictionaries, and other reference sources. Reference sources provide background information on a topic, clarify definitions, and often include bibliographies which cite books and journal articles.
Books can be a good place to find an overview of a topic. References to journal articles and books can often be found in a bibliography at the end of a chapter. Since journal articles are often more focused than books, they may provide more specific information than books. References to additional articles and books can often be found in a bibliography at the end of an article.