Ireland, S. (2010). PET Direct Workbook with Answers. Cambridge University Press.
Chicago Style aipamenaIreland, Sue. PET Direct Workbook With Answers. Cambridge University Press, 2010.
MLA aipamenaIreland, Sue. PET Direct Workbook With Answers. Cambridge University Press, 2010.
Kontuz: berrikusi erreferentzia hauek erabili aurretik.