Finding a Plagiarized Paper Online
1. Use popular search engines such as Google to search for a phrase from the paper because titles are often changed. If you surround your phrase with quotation marks, these search engines can search the text of other web pages for the exact wording used in your student's paper. 
2. Search SPC's full text databases for articles on the same topic. Literature Resource Center, Academic Search Complete, and  Academic Onefile are all excellent sources of full text resources.
3. There are a number of services that will search out sources of plagiarized papers for a fee. You can learn more about these services from the links that follow.

More information:

Cheating 101: Paper Mills and You  Designed by the Kimbel Library at Coastal Carolina University

Plagiarism and the Web Created by Western Illinois University Resources from, a plagiarism detection software product

Plagiarism Tutorial from San José State University