APA (7th ed.) Citation

Hawking, L., Hawking, S., & Parsons, G. (2014). George and the unbreakable code. Doubleday.

Chicago Style (17th ed.) Citation

Hawking, Lucy, Stephen Hawking, and Garry Parsons. George and the Unbreakable Code. London: Doubleday, 2014.

MLA (9th ed.) Citation

Hawking, Lucy, et al. George and the Unbreakable Code. Doubleday, 2014.