Clifford, N., Holloway, S. L., Rice, S. P., & Valentine, G. (2009). Key concepts in Geography (2a. ed.). SAGE Publications.

Clifford, Nicholas, Sarah L. Holloway, Stephen P. Rice, and Gill Valentine. Key Concepts in Geography. 2a. ed. Los Angeles: SAGE Publications, 2009.

Clifford, Nicholas, et al. Key Concepts in Geography. 2a. ed. SAGE Publications, 2009.