Educational Testing Service. (2021). Official guide to the toefl ibt test, sixth edition (Sixth edition.). McGraw Hill.
Citação do estilo Chicago (17ª ed.)Educational Testing Service. Official Guide to the Toefl Ibt Test, Sixth Edition. Sixth edition. New York: McGraw Hill, 2021.
Citação MLA (9ª ed.)Educational Testing Service. Official Guide to the Toefl Ibt Test, Sixth Edition. Sixth edition. McGraw Hill, 2021.
Nota: a formatação da citação pode não corresponder 100% ao definido pela respectiva norma.