Cita APA (7th ed.)

Ferree, T., & Sanabria, K. (1998). NorthStar: Focus on listening and speaking, high intermediate. Longman.

Cita Chicago (17th ed.)

Ferree, Tess, i Kim Sanabria. NorthStar: Focus on Listening and Speaking, High Intermediate. Nueva York: Longman, 1998.

Cita MLA (9th ed.)

Ferree, Tess, i Kim Sanabria. NorthStar: Focus on Listening and Speaking, High Intermediate. Longman, 1998.