Cita APA (7a ed.)
Harris, M., Mower, D., & Sikorzynska, A. Opportunities: Pre-Intermediate : Student's Book. Pearson.
Cita estilo Chicago (17a ed.)
Harris, Michael, David Mower, y Anna Sikorzynska. Opportunities: Pre-Intermediate : Student's Book. Harlow, Inglaterra: Pearson.
Cita MLA (9a ed.)
Harris, Michael, et al. Opportunities: Pre-Intermediate : Student's Book. Pearson.
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