Cita APA (7th ed.)

Gairns, R., & Redman, S. (2006). Natural English: Pre-intermediate student's book. Oxford University Press.

Cita Chicago (17th ed.)

Gairns, Ruth, i Stuart Redman. Natural English: Pre-intermediate Student's Book. Oxford: Oxford University Press, 2006.

Cita MLA (8th ed.)

Gairns, Ruth, i Stuart Redman. Natural English: Pre-intermediate Student's Book. Oxford University Press, 2006.