1. Open the Advanced Search button ( http://images.mobilism.org/?dm=V2K9 ) in v2.0, or ( http://images.mobilism.org/?dm=D7HWDULP ) in classic.
2. Enter the word "Children" or "Non-fiction" as keyword
3. Select Audiobooks on the "Search in forums" drop-down menu
4. Tick the option "Message text only" in the option "Search within".
More info here: Frequently Asked Questions (F.A.Q.s) Tricks, and Tips
And here: eBook Help Desk