APA (7th ed.) Citation

Abbs, B., & Sexton, M. Challenges: A multi-media project for learners of English. Langenscheidt-Longman.

Chicago Style (17th ed.) Citation

Abbs, Brian, and Malcolm Sexton. Challenges: A Multi-media Project for Learners of English. [München]: Langenscheidt-Longman.

MLA (9th ed.) Citation

Abbs, Brian, and Malcolm Sexton. Challenges: A Multi-media Project for Learners of English. Langenscheidt-Longman.