Cita APA (7a ed.)

Obee, B., & Evans, V. (2003). Upstream: Upper intermediate. Express Publishing.

Cita Chicago Style (17a ed.)

Obee, Bob, y Virginia Evans. Upstream: Upper Intermediate. Newbury: Express Publishing, 2003.

Cita MLA (8a ed.)

Obee, Bob, y Virginia Evans. Upstream: Upper Intermediate. Express Publishing, 2003.