Cita APA (7th ed.)

Scott L. Lyn & Scott D. David. (2011). Natural English. Upper-intermediate: Workbook with key. New York, Oxford University Press, 2011.

Cita Chicago (17th ed.)

Scott L. Lyn i Scott D. David. Natural English. Upper-intermediate: Workbook with Key. New York, Oxford University Press, 2011, 2011.

Cita MLA (9th ed.)

Scott L. Lyn i Scott D. David. Natural English. Upper-intermediate: Workbook with Key. New York, Oxford University Press, 2011, 2011.