Here is a link to a list of concordencer software, some of them are free and
others you have to pay for. It is a blessing because it is surprising how
easy it is to miss words buried deep inside an article or short story that
appear out of no where when you run the text through these programs. It was
one more tool that made my job easier. In addition to identifying obstacles,
it can be used to create vocabulary lists and I have even edited a few
articles to insert simpler synonyms for lower level classes.

http://www.corpus-linguistics.de/html/nav/soft/conc.html

I hope this helps.

John