Cita APA (7a ed.)

Harris, M., Sikorzynska, A., & Mower, D. (2003). Opportunities pre-intermediate: Pre-intermediate. Pearson Education.

Cita Chicago Style (17a ed.)

Harris, Michael, Anna Sikorzynska, y David Mower. Opportunities Pre-intermediate: Pre-intermediate. Harlow: Pearson Education, 2003.

Cita MLA (8a ed.)

Harris, Michael, et al. Opportunities Pre-intermediate: Pre-intermediate. Pearson Education, 2003.