APA (7th ed.) Citation

Abbs, B., & Freebairn, I. B. (2005). Sky 1: Student's book.

Chicago Style (17th ed.) Citation

Abbs, Brian, and Ingrid Bygrave Freebairn. Sky 1: Student's Book. Harlow, 2005.

MLA (9th ed.) Citation

Abbs, Brian, and Ingrid Bygrave Freebairn. Sky 1: Student's Book. 2005.