Walton, R. (2000). Initiative: A course for advanced learners. Cambridge: Cambridge University Press.
Chicago Style aipamenaWalton, Richard. Initiative: A Course for Advanced Learners. Cambridge: Cambridge University Press, 2000.
MLA aipamenaWalton, Richard. Initiative: A Course for Advanced Learners. Cambridge: Cambridge University Press, 2000.
Kontuz: berrikusi erreferentzia hauek erabili aurretik.