Plagiarism
Current advice suggests using the Google Advanced Search engine, and type in the suspicious phrase under "with the exact phrase"
The New Plagiarism: Seven Antidotes to Prevent Highway Robbery in an Electronic Age
Cheating 101: Paper Mills and You
Here are three sites I came across for checking for plagiarism. I believe the first one is the best.
Plagiarism.com
Free. Is it possible to prevent plagiarism by determining if a term paper has been copied from the Internet or from another class? It is now.Essay Verification Engine.
Free Trial Period. CaNexus Web Design is proud to bring you EVE, the Essay Verification Engine. EVE is a powerful tool designed to combat the growing problem of Internet plagiarism. EVE accepts essays in plain text format and returns links to web pages from which a student may have plagiarized. EVE has been developed to be powerful enough to find plagiarized material while not overwhelming the professor with false links. Try EVE by giving it an essay in plain text (.txt) format. Next, find some similar material on the web, copy a couple of paragraphs into the essay, and give the new essay to EVE. In our testing, EVE found approximately 80-90% of plagiarized material. http://www.canexus.com/eve