Stephenson, H., Dummett, P., & Hughes, J. (2014). Life: Beginner. Student's book (1a. ed.). National Geographic Learning.
Chicago Style (17th ed.) ZitazioaStephenson, Helen, Paul Dummett, eta John Hughes. Life: Beginner. Student's Book. 1a. ed. Hampshire: National Geographic Learning, 2014.
MLA (9th ed.) ZitazioaStephenson, Helen, et al. Life: Beginner. Student's Book. 1a. ed. National Geographic Learning, 2014.
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