APA Edition Citation

Hawking, L., & Hawking, S. (2019). George and the unbreakable code. Penguin books.

Chicago Edition Citation

Hawking, Lucy, and Stephen Hawking. George and the Unbreakable Code. UK: Penguin books, 2019.

MLA Edition Citation

Hawking, Lucy, and Stephen Hawking. George and the Unbreakable Code. Penguin books, 2019.

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