My son is absolutely enthralled by your books. He's read all of SS (and can't wait until 4/30), MBA series, and is on Pandemonium since March! I've never seen him read this quickly before. He's also taking Accelerated Reader quizzes so I know he's understanding them. My question (and panic-haha) is what to read next. Do you have any authors that you recommend for a 9 year old who loves your books?