I have no idea where that might be, but I agree with the above comments that it really should be very easy to avoid writing Mary Sue's. It is indeed the defects and flaws which help to keep it away from being a Mary Sue, as well as usually making the story more interesting to read. Perfect characters are only interesting to the person that wrote it.
But on the other hand, as long as those flaws aren't simply the usual teenaged "flaw", such as being moody and surly, antisocial and without friends. My god, that's so boring to read! Try being a little more creative than that. Otherwise, it just takes common sense to avoid blatant Mary Sue's.