Cita APA (7th ed.)

Stephenson, H. (2013). Life: Intermediate. Workbook (1a. ed.). National Geographic Learning.

Cita Chicago (17th ed.)

Stephenson, Helen. Life: Intermediate. Workbook. 1a. ed. Hampshire: National Geographic Learning, 2013.

Cita MLA (9th ed.)

Stephenson, Helen. Life: Intermediate. Workbook. 1a. ed. National Geographic Learning, 2013.