APA (7th ed.) Citation

Keene, C. (1981). The clue in the crossword cipher. Armada books.

Chicago Style (17th ed.) Citation

Keene, Carolyn. The Clue in the Crossword Cipher. New York: Armada books, 1981.

MLA (9th ed.) Citation

Keene, Carolyn. The Clue in the Crossword Cipher. Armada books, 1981.