Question: Anna Banks is an American author, best known for her New York Times best selling "Syrena Legacy" series, Mad Hatter Entertainment, producer on the "How to Train Your Dragon" franchise, has acquired movie rights to her series, How to Train Your Dragon is a series of how many children's books written by British author Cressida Cowell?
Sentence (from "How to Train Your Dragon"): How to Train Your Dragon is a series of twelve children's books written by British author Cressida Cowell.
Relevant evidence: Yes