APA-Zitierstil (7. Ausg.)

Brown, H. D., Cohen, D. S., & O'Day, J. (1991). Challenges: A process approach to academic English. Prentice Hall.

Chicago-Zitierstil (17. Ausg.)

Brown, H. Douglas, Deborah S. Cohen, und Jennifer O'Day. Challenges: A Process Approach to Academic English. Upper Saddle River, NJ: Prentice Hall, 1991.

MLA-Zitierstil (9. Ausg.)

Brown, H. Douglas, et al. Challenges: A Process Approach to Academic English. Prentice Hall, 1991.