Cita APA (7a ed.)

Dean, M., & Johnston, O. (2001). Opportunities elementary: Language powerbook. Pearson Education.

Cita Chicago Style (17a ed.)

Dean, Michael, y Olivia Johnston. Opportunities Elementary: Language Powerbook. Harlow: Pearson Education, 2001.

Cita MLA (8a ed.)

Dean, Michael, y Olivia Johnston. Opportunities Elementary: Language Powerbook. Pearson Education, 2001.