There is a book thread here with lots of suggestions
www.chinaberry.com, lots of nice books here
http://www.commonsensemedia.org, this has book review, talks about content, I keep this in my favorites.
You may want to read the first book in these series to make sure these are ok for your DS4.
Comet in Moominland, This is one series by Tove Jansson
Puppy Place by Ellen Miles
Books by Janet Brett, wonderful illustrations
The Mysterious Cheese Thief, Series by Geronimo Stilton
Nate the Great, a little easier than Magic Tree House
Cara the camp fairy / by Daisy Meadows. This series looks girly but my son liked them too.
