Citazione Stile APA (7a Edizione)

Obee B. Bob & Evans V. Virginia. (2009). Upstream. Upper-Intermediate B2+: Workbook: Student's Book (6-th ed.). Newbury, Express Publishing, 2009.

Citazione stile Chigago Style (17a edizione)

Obee B. Bob e Evans V. Virginia. Upstream. Upper-Intermediate B2+: Workbook: Student's Book. 6-th ed. Newbury, Express Publishing, 2009, 2009.

Citatione MLA (9a ed.)

Obee B. Bob e Evans V. Virginia. Upstream. Upper-Intermediate B2+: Workbook: Student's Book. 6-th ed. Newbury, Express Publishing, 2009, 2009.