Cita APA (7th ed.)

Hughes, J., Stephenson, H., & Dummett, P. (2013). Life: Pre-Intermediate. Student's Book (1a. ed.). National Geographic Learning.

Cita Chicago (17th ed.)

Hughes, John, Helen Stephenson, i Paul Dummett. Life: Pre-Intermediate. Student's Book. 1a. ed. Hampshire: National Geographic Learning, 2013.

Cita MLA (9th ed.)

Hughes, John, et al. Life: Pre-Intermediate. Student's Book. 1a. ed. National Geographic Learning, 2013.