It's tempting to use another student's work - you can easily find sample papers and essays online. The work of finding and analyzing sources has been done for you. And the source hasn't been published so it's not a "real" source you have to cite? Right?
NOPE - you need to do your own leg-work.
Helpful Hint
Use bibliographies or works cited pages from papers to identify sources to track down. Even better, find more authoritative sources like journal articles, encyclopedia entries, or books and look for lists of works cited in those.