Cita APA (7th ed.)

Gairns R. Ruth & Redman S. Stuart. (2004). Natural English. Intermediate: Student's book. New York, Oxford University Press, 2004.

Cita Chicago (17th ed.)

Gairns R. Ruth i Redman S. Stuart. Natural English. Intermediate: Student's Book. New York, Oxford University Press, 2004, 2004.

Cita MLA (9th ed.)

Gairns R. Ruth i Redman S. Stuart. Natural English. Intermediate: Student's Book. New York, Oxford University Press, 2004, 2004.