Citazione Stile APA (7a Edizione)

Osborne, C. l. First certificate practice tests (1. ed.). Cengage Learning.

Citazione stile Chigago Style (17a edizione)

Osborne, Charles linguista. First Certificate Practice Tests. 1. ed. Cengage Learning.

Citatione MLA (9a ed.)

Osborne, Charles linguista. First Certificate Practice Tests. 1. ed. Cengage Learning.