Richards, J. C., Hull, J., & Proctor, S. (2005). Interchange: Workbook 1 B (1a. ed.). Cambridge University.

Richards, Jack C., Jonathan Hull, and Susan Proctor. Interchange: Workbook 1 B. 1a. ed. Nueva York: Cambridge University, 2005.

Richards, Jack C., et al. Interchange: Workbook 1 B. 1a. ed. Cambridge University, 2005.