APA (7th ed.) Citation

Ashton, H., & Shepherd, S. (2012). Work on your accent. Collins.

Chicago Style (17th ed.) Citation

Ashton, Helen, and Sarah Shepherd. Work on Your Accent. London: Collins, 2012.

MLA (9th ed.) Citation

Ashton, Helen, and Sarah Shepherd. Work on Your Accent. Collins, 2012.

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