APA (7th ed.) Citation

Busby, A., & Ross, M. The Ugly duckling. Penguin Books Ltd.

Chicago Style (17th ed.) Citation

Busby, Ailie, and Mandy Ross. The Ugly Duckling. London: Penguin Books Ltd.

MLA (9th ed.) Citation

Busby, Ailie, and Mandy Ross. The Ugly Duckling. Penguin Books Ltd.

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