Even if you just used a particular book or web site for background research, you should include it in your Works Cited page.
HOW TO CITE: COMPOSITION OF A CITATION
Different elements of a citation are required for each of the various types of resources you use. The citation style you use (MLA, APA, Chicago, etc.) dictates what is required and how it is formatted, but basic citation elements remain fairly consistent across citation styles.
For books: author, title, publisher, place of publication, and publication date.
For articles: author, date, article title, journal title, journal volume and issue, and page numbers.
HOW TO CITE: CITATION STYLE GUIDES
MLA, APA, and Chicago are three of the main citation styles used for writing and formatting research papers. Ask your instructor if you are unsure about which style to use and what guidebook, web resource, etc. to use to locate citation rules and examples.
The OWL at Purdue: MLA Formatting and Citation Guide
The OWL at Purdue: APA Formatting and Citation Guide
For tools to help you format your works cited page or to organize your citations, see:
Citation Management Tools