Emotionally Charged Learning.
childrens books
a lot.
Eric Walters wrote 61 books.
Cornelia Funk, the author of Inkhert writes about a book in her book Inkheart. There are more but i don't feel like naming them
It actually depends. You would use which if you were asking what book they wrote among a certain selection of books. You would use what if you were just asking in general.