Reference materials provide background information on a topic, work, or author. Reference materials in literary studies may be fairly specific, e.g. The Oxford companion to Shakespeare, or they can be broader and contain specific entries, e.g. Twentieth-Century Literary Criticism with an entry about Sandra Cisneros. Reference materials are a good place to start when beginning your research because they can give you a basic understanding of the writer you are researching and direct you to important critics.