APA (7th ed.) Citation

Martin, B. (1975). A hydra goes walking: A little nature book. Encyclopaedia Britannica Educational Corp..

Chicago Style (17th ed.) Citation

Martin, Bill. A Hydra Goes Walking: A Little Nature Book. Chicago, Ill.: Encyclopaedia Britannica Educational Corp., 1975.

MLA (9th ed.) Citation

Martin, Bill. A Hydra Goes Walking: A Little Nature Book. Encyclopaedia Britannica Educational Corp., 1975.