APA (7th ed.) Citation

Musso, G., Aitken, A., & Brown, A. (2011). Where would I be without you? Gallic Books.

Chicago Style (17th ed.) Citation

Musso, Guillaume, Anna Aitken, and Anna Brown. Where Would I Be Without You? London: Gallic Books, 2011.

MLA (9th ed.) Citation

Musso, Guillaume, et al. Where Would I Be Without You? Gallic Books, 2011.