The answer is "They point the reader to a more detailed listing on the Works Cited page." A listing of source material is too long. If you can look up the text cited outside of a works cited page, the citation is most likely too long or incorrect. An author's name can always be included outside of a parentheses. For example, in the essay I am currently writing, I put: "In Annie Dillard’s An American Childhood, Dillard depicts, in detail, the personality and characteristics of her mother."