Comparing 2 Fields--Looking For Differences

Hello,
I have 2 fields that are supposed to have the same information for each record. I got the information from different sources, which is the reason for having 2 fields. I wanted to make sure that the information was accurate. Turns out, that some of it isn't accurate--all the fields don't match.

Here's a little example of what I have:

|___TITLE___|___ISSN 1___|___ISSN 2___|
|__TITLE 1__|__12345678__|__12345678__|
|__Title 2__|__22224444__|__23224322__|
|__Title 3__|__98765432__|__98765432__|

As you can see, the ISSN numbers for Title 1 and 3 match. There's no problem there. I want a query that would list all those like Title 2, where the ISSN numbers don't match. Then I'd have a list of all of the problem Titles, and I could look up the real ISSN numbers.

Thanks

-Siena