Citazione Stile APA (7a Edizione)

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

Citazione stile Chigago Style (17a edizione)

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

Citatione MLA (9a ed.)

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