APA aipamena

 Stephenson, H. (2020). Life A2- B1: Student's book.  National geographic learning.

Chicago Style aipamena

 Stephenson, Helen. Life A2- B1: Student's Book.  National geographic learning, 2020.

MLA aipamena

 Stephenson, Helen. Life A2- B1: Student's Book.  National geographic learning, 2020.

Kontuz: berrikusi erreferentzia hauek erabili aurretik.