APA (7th ed.) Citation

Sayer, M., Dellar, H., & Walkley, A. (2016). Outcome: Intermediate Teacher's Book. National Geographic Learning Cengage Learning.

Chicago Style (17th ed.) Citation

Sayer, Mike, Hugh Dellar, and Andrew Walkley. Outcome: Intermediate Teacher's Book. United Kingdom: National Geographic Learning Cengage Learning, 2016.

MLA (9th ed.) Citation

Sayer, Mike, et al. Outcome: Intermediate Teacher's Book. National Geographic Learning Cengage Learning, 2016.