Jakeman, V. (2004). Step up to IELTS. Cambridge University Press.
Chicago Style aipamenaJakeman, Vanessa. Step Up to IELTS. Cambridge: Cambridge University Press, 2004.
MLA aipamenaJakeman, Vanessa. Step Up to IELTS. Cambridge University Press, 2004.
Kontuz: berrikusi erreferentzia hauek erabili aurretik.