Bowler, B., & Parminter, S. (1992). Headway, Pre-Intermediate: Pronunciation. Oxford: Oxford University Press.
Chicago Style aipamenaBowler, Bill, và Sue Parminter. Headway, Pre-Intermediate: Pronunciation. Oxford: Oxford University Press, 1992.
MLA aipamenaBowler, Bill, và Sue Parminter. Headway, Pre-Intermediate: Pronunciation. Oxford: Oxford University Press, 1992.
Kontuz: berrikusi erreferentzia hauek erabili aurretik.