Loungheed, L. (2011). Barron's IELTS: International English language testing system (2nd ed.). New Age Intenational.
Chicago-viite (17. p.)Loungheed, Lin. Barron's IELTS: International English Language Testing System. 2nd ed. New Delhi: New Age Intenational, 2011.
MLA-viite (8. p.)Loungheed, Lin. Barron's IELTS: International English Language Testing System. 2nd ed. New Age Intenational, 2011.
Varoitus: Nämä viitteet eivät aina ole täysin luotettavia.