Alex Luppens-Dale writes: “How many Baby-Sitters Club books did you read? How about Sweet Valley High? Animorphs? I loved a long-running series of the kind that doesn’t seem to really exist anymore. How did the authors do it? Magic, right? Sure. The magic of ghostwriting. Maintaining continuity was a challenge, and many series would have a ‘series Bible.’ The Baby-Sitters Club series Bible was constructed by none other than YA juggernaut David Levithan early in his career at Scholastic. [Animorphs creator] Katherine Applegate herself also wrote for Sweet Valley.”