Encyclopedias, dictionaries, and other reference resources help you to discover basic information—names, dates, definitions, summaries, etc. These are good places to start when beginning research on an unfamiliar subject, and when choosing or narrowing a paper topic.
Reading a literary work set in an unfamiliar time period or location? Seeing terms or concepts that are new to you? Reference works can help provide a brief introduction to countries and their histories as well as get you quickly up to speed on the meaning of new terms and concepts. Knowing this information can bring an added layer of meaning to a literary work.