Educational Testing Service. (2021). The official guide to the Toefl IBT test (6th ed.). New York: McGraw Hill.
Stile di citazione ChicagoEducational Testing Service. The Official Guide to the Toefl IBT Test. 6th ed. New York: McGraw Hill, 2021.
Citazione MLAEducational Testing Service. The Official Guide to the Toefl IBT Test. 6th ed. New York: McGraw Hill, 2021.
Attenzione: Queste citazioni potrebbero non essere precise al 100%.