APA (7th ed.) Citation

Enid Blyton. (1943). The Mystery of the Secret Room. Hodder Children's Books.

Chicago Style (17th ed.) Citation

Enid Blyton. The Mystery of the Secret Room. New York: Hodder Children's Books, 1943.

MLA (9th ed.) Citation

Enid Blyton. The Mystery of the Secret Room. Hodder Children's Books, 1943.