Educational Testing Service. (2021). Official guide to the toefl ibt test, sixth edition (Sixth edition.). McGraw Hill.
Citazione stile Chigago Style (17a edizione)Educational Testing Service. Official Guide to the Toefl Ibt Test, Sixth Edition. Sixth edition. New York: McGraw Hill, 2021.
Citatione MLA (9a ed.)Educational Testing Service. Official Guide to the Toefl Ibt Test, Sixth Edition. Sixth edition. McGraw Hill, 2021.
Attenzione: Queste citazioni potrebbero non essere precise al 100%.