Reference books include biographical dictionaries, historical dictionaries, encyclopedias, atlases, and statistical summaries.

Utilize reference books:

• To confirm background facts (such as names, dates, places) and determine what is "common knowledge" information (i.e facts that have enough universal agreement they do not need citations) 
• To inform yourself about historical context surrounding your topic and about significant people or events related to your topic.
• For their bibliographies, which often suggest important secondary studies.

Bibliographies, footnotes and suggested readings sections of scholarship you read in class can point you in the direction of appropriate starting places for your individual research as well.