APA (7th ed.) Citation

Blyton, E. (2007). The naughtiest girl keeps a secret. Hodder Children's Books.

Chicago Style (17th ed.) Citation

Blyton, Enid. The Naughtiest Girl Keeps a Secret. London: Hodder Children's Books, 2007.

MLA (9th ed.) Citation

Blyton, Enid. The Naughtiest Girl Keeps a Secret. Hodder Children's Books, 2007.

Warning: These citations may not always be 100% accurate.