Παραπομπή σε μορφή APA (7η εκδ.)

Abbs, B., & Freebairn, I. Opening strategies: An integrated language course for beginners of English. Longman.

Παραπομπή σε μορφή Chicago (17η εκδ.)

Abbs, Brian, και Ingrid Freebairn. Opening Strategies: An Integrated Language Course for Beginners of English. Harlow: Longman.

Παραπομπή σε μορφή MLA (9th εκδ.)

Abbs, Brian, και Ingrid Freebairn. Opening Strategies: An Integrated Language Course for Beginners of English. Longman.